diff --git a/composer.json b/composer.json
index b190dda..dd5d178 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,8 @@
 		"voku/portable-utf8": "^5.4|^6.0"
 	},
 	"require-dev":{
-		"phpunit/phpunit": "^9.0"
+		"phpunit/phpunit": "^9.0",
+		"rector/rector": "^2.4"
 	},
 	"autoload": {
 		"psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 5c62690..1ae984c 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,6 +1,6 @@
-<?xml version="1.0" encoding="UTF-8" ?>
+<?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
          backupGlobals="false"
          colors="true"
          beStrictAboutChangesToGlobalState="true"
@@ -9,16 +9,14 @@
          beStrictAboutTodoAnnotatedTests="true"
          verbose="true"
          bootstrap="vendor/autoload.php">
-
+    <coverage>
+        <include>
+            <directory>src</directory>
+        </include>
+    </coverage>
     <testsuites>
         <testsuite name="functional">
             <directory suffix=".php">test</directory>
         </testsuite>
     </testsuites>
-
-    <filter>
-        <whitelist>
-            <directory>src</directory>
-        </whitelist>
-    </filter>
 </phpunit>
diff --git a/rector.php b/rector.php
new file mode 100644
index 0000000..ed98e17
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+
+return RectorConfig::configure()
+    ->withPaths([
+        __DIR__ . '/src',
+        __DIR__ . '/test',
+    ])
+    // uncomment to reach your current PHP version
+    ->withPhpSets(
+        php85: true
+    )
+    ->withPreparedSets(
+        codeQuality: true,
+        deadCode: true,
+        typeDeclarations: true,
+    )
+    ->withComposerBased(
+        phpunit: true,
+    )
+    ;
diff --git a/src/NotFoundException.php b/src/NotFoundException.php
index b26fe39..a18c717 100644
--- a/src/NotFoundException.php
+++ b/src/NotFoundException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Wamania\Snowball;
 
 class NotFoundException extends \Exception
diff --git a/src/Stemmer/Catalan.php b/src/Stemmer/Catalan.php
index b1de0ab..d6c341a 100644
--- a/src/Stemmer/Catalan.php
+++ b/src/Stemmer/Catalan.php
@@ -84,7 +84,7 @@ class Catalan extends Stem
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -106,7 +106,7 @@ public function stem($word)
 
         // Step 1b: Verb suffix
         // Do step 1b if no ending was removed by step 1a.
-        if ($this->word == $word) {
+        if ($this->word === $word) {
             $this->step1b();
         }
 
@@ -123,13 +123,11 @@ public function stem($word)
      * and delete it in R1.
      */
 
-    private function step0()
+    private function step0(): bool
     {
-        if (($position = $this->search(static::$attached_pronoun)) !== false) {
-            if ($this->inR1($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->search(static::$attached_pronoun) !== false && $this->inR1($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
         return false;
     }
@@ -137,7 +135,7 @@ private function step0()
     /**
      * Step 1a: Standard suffix
      */
-    private function step1a()
+    private function step1a(): bool
     {
         // Run step 1a.2 before 1a.1, since they overlap on `cions` (1a.1) and `acions` (1a.2)
         //
@@ -213,7 +211,7 @@ private function step1a()
      *      Search for the longest among the following suffixes in r1 and r2, and
      *      perform the action indicated.
      */
-    private function step1b()
+    private function step1b(): bool
     {
         // Step 1b.1
         //
@@ -263,7 +261,7 @@ private function step1b()
      * Search for the longest among the following suffixes in R1, and perform
      * the action indicated.
      */
-    private function step2()
+    private function step2(): bool
     {
         // Step 2.1
         // residual suffix
@@ -292,7 +290,7 @@ private function step2()
      * And finally:
      * Remove accents and l aggeminades
      */
-    private function finish()
+    private function finish(): void
     {
         $this->word = str_replace(
             ['á', 'é', 'í', 'ó', 'ú', 'à', 'è', 'ì', 'ò', 'ï', 'ü', '·'],
diff --git a/src/Stemmer/Danish.php b/src/Stemmer/Danish.php
index c539fdb..09a91b8 100644
--- a/src/Stemmer/Danish.php
+++ b/src/Stemmer/Danish.php
@@ -15,7 +15,7 @@ class Danish extends Stem
     /**
      * All danish vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'æ', 'å', 'ø');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'æ', 'å', 'ø'];
 
     /**
      * {@inheritdoc}
@@ -52,41 +52,41 @@ public function stem($word): string
      * a   b   c   d   f   g   h   j   k   l   m   n   o   p   r   t   v   y   z   å
      *
      * @param string $ending
-     * @return boolean
      */
-    private function hasValidSEnding($word)
+    private function hasValidSEnding(string $word): bool
     {
         $lastLetter = UTF8::substr($word, -1, 1);
-        return in_array($lastLetter, array('a', 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y', 'z', 'å'));
+        return in_array($lastLetter, ['a', 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y', 'z', 'å']);
     }
 
     /**
      * Step 1
      * Search for the longest among the following suffixes in R1, and perform the action indicated.
      */
-    private function step1()
+    private function step1(): ?bool
     {
         // hed   ethed   ered   e   erede   ende   erende   ene   erne   ere   en   heden   eren   er   heder   erer
         // heds   es   endes   erendes   enes   ernes   eres   ens   hedens   erens   ers   ets   erets   et   eret
         //      delete
-        if ( ($position = $this->searchIfInR1(array(
+        if ( ($position = $this->searchIfInR1([
             'erendes', 'erende', 'hedens', 'erede', 'ethed', 'heden', 'endes', 'erets', 'heder', 'ernes',
             'erens', 'ered', 'ende', 'erne', 'eres', 'eren', 'eret', 'erer', 'enes', 'heds',
             'ens', 'ene', 'ere', 'ers', 'ets', 'hed', 'es', 'et', 'er', 'en', 'e'
-        ))) !== false) {
+        ])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         // s
         //      delete if preceded by a valid s-ending
-        if ( ($position = $this->searchIfInR1(array('s'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['s'])) !== false) {
             $word = UTF8::substr($this->word, 0, $position);
             if ($this->hasValidSEnding($word)) {
                 $this->word = $word;
             }
             return true;
         }
+        return null;
     }
 
     /**
@@ -94,9 +94,9 @@ private function step1()
      * Search for one of the following suffixes in R1, and if found delete the last letter.
      *      gd   dt   gt   kt
      */
-    private function step2()
+    private function step2(): void
     {
-        if ($this->searchIfInR1(array('gd', 'dt', 'gt', 'kt')) !== false) {
+        if ($this->searchIfInR1(['gd', 'dt', 'gt', 'kt']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
     }
@@ -104,17 +104,17 @@ private function step2()
     /**
      * Step 3:
      */
-    private function step3()
+    private function step3(): ?bool
     {
         // If the word ends igst, remove the final st.
-        if ($this->search(array('igst')) !== false) {
+        if ($this->search(['igst']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -2);
         }
 
         // Search for the longest among the following suffixes in R1, and perform the action indicated.
         //  ig   lig   elig   els
         //      delete, and then repeat step 2
-        if ( ($position = $this->searchIfInR1(array('elig', 'lig', 'ig', 'els'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['elig', 'lig', 'ig', 'els'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             $this->step2();
             return true;
@@ -122,16 +122,17 @@ private function step3()
 
         //  løst
         //      replace with løs
-        if ($this->searchIfInR1(array('løst')) !== false) {
+        if ($this->searchIfInR1(['løst']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
+        return null;
     }
 
     /**
      * Step 4: undouble
      * If the word ends with double consonant in R1, remove one of the consonants.
      */
-    private function step4()
+    private function step4(): bool
     {
         $length = UTF8::strlen($this->word);
         if (!$this->inR1(($length-1))) {
diff --git a/src/Stemmer/Dutch.php b/src/Stemmer/Dutch.php
index 8fba0d6..05a8e7d 100644
--- a/src/Stemmer/Dutch.php
+++ b/src/Stemmer/Dutch.php
@@ -15,7 +15,7 @@ class Dutch extends Stem
     /**
      * All dutch vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'è');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'è'];
 
     /**
      * {@inheritdoc}
@@ -31,8 +31,8 @@ public function stem($word)
 
         // First, remove all umlaut and acute accents.
         $this->word = str_replace(
-            array('ä', 'ë', 'ï', 'ö', 'ü', 'á', 'é', 'í', 'ó', 'ú'),
-            array('a', 'e', 'i', 'o', 'u', 'a', 'e', 'i', 'o', 'u'),
+            ['ä', 'ë', 'ï', 'ö', 'ü', 'á', 'é', 'í', 'ó', 'ú'],
+            ['a', 'e', 'i', 'o', 'u', 'a', 'e', 'i', 'o', 'u'],
             $this->word);
 
         $this->plainVowels = implode('', self::$vowels);
@@ -67,12 +67,11 @@ public function stem($word)
     /**
      * Define a valid s-ending as a non-vowel other than j.
      * @param string $ending
-     * @return boolean
      */
-    private function hasValidSEnding($word)
+    private function hasValidSEnding(string $word): bool
     {
         $lastLetter = UTF8::substr($word, -1, 1);
-        return !in_array($lastLetter, array_merge(self::$vowels, array('j')));
+        return !in_array($lastLetter, array_merge(self::$vowels, ['j']));
     }
 
     /**
@@ -80,7 +79,7 @@ private function hasValidSEnding($word)
      * @param string $ending
      * @return boolean
      */
-    private function hasValidEnEnding($word)
+    private function hasValidEnEnding(string $word)
     {
         $lastLetter = UTF8::substr($word, -1, 1);
         if (in_array($lastLetter, self::$vowels)) {
@@ -88,18 +87,15 @@ private function hasValidEnEnding($word)
         }
 
         $threeLastLetters = UTF8::substr($word, -3, 3);
-        if ($threeLastLetters == 'gem') {
-            return false;
-        }
-        return true;
+        return $threeLastLetters != 'gem';
     }
 
     /**
      *  Define undoubling the ending as removing the last letter if the word ends kk, dd or tt.
      */
-    private function unDoubling()
+    private function unDoubling(): void
     {
-        if ($this->search(array('kk', 'dd', 'tt')) !== false) {
+        if ($this->search(['kk', 'dd', 'tt']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
     }
@@ -108,11 +104,11 @@ private function unDoubling()
      * Step 1
      * Search for the longest among the following suffixes, and perform the action indicated
      */
-    private function step1()
+    private function step1(): bool
     {
         // heden
         //      replace with heid if in R1
-        if ( ($position = $this->search(array('heden'))) !== false) {
+        if ( ($position = $this->search(['heden'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(heden)$#u', 'heid', $this->word);
             }
@@ -121,7 +117,7 @@ private function step1()
 
         // en   ene
         //      delete if in R1 and preceded by a valid en-ending, and then undouble the ending
-        if ( ($position = $this->search(array('ene', 'en'))) !== false) {
+        if ( ($position = $this->search(['ene', 'en'])) !== false) {
             if ($this->inR1($position)) {
                 $word = UTF8::substr($this->word, 0, $position);
                 if ($this->hasValidEnEnding($word)) {
@@ -134,7 +130,7 @@ private function step1()
 
         // s   se
         //      delete if in R1 and preceded by a valid s-ending
-        if ( ($position = $this->search(array('se', 's'))) !== false) {
+        if ( ($position = $this->search(['se', 's'])) !== false) {
             if ($this->inR1($position)) {
                 $word = UTF8::substr($this->word, 0, $position);
                 if ($this->hasValidSEnding($word)) {
@@ -151,17 +147,15 @@ private function step1()
      * Step 2
      * Delete suffix e if in R1 and preceded by a non-vowel, and then undouble the ending
      */
-    private function step2()
+    private function step2(): bool
     {
-        if ( ($position = $this->search(array('e'))) !== false) {
-            if ($this->inR1($position)) {
-                $letter = UTF8::substr($this->word, -2, 1);
-                if (!in_array($letter, self::$vowels)) {
-                    $this->word = UTF8::substr($this->word, 0, $position);
-                    $this->unDoubling();
+        if ($position = $this->search(['e']) !== false && $this->inR1($position)) {
+            $letter = UTF8::substr($this->word, -2, 1);
+            if (!in_array($letter, self::$vowels)) {
+                $this->word = UTF8::substr($this->word, 0, $position);
+                $this->unDoubling();
 
-                    return true;
-                }
+                return true;
             }
         }
 
@@ -172,22 +166,18 @@ private function step2()
      * Step 3a: heid
      * delete heid if in R2 and not preceded by c, and treat a preceding en as in step 1(b)
      */
-    private function step3a()
+    private function step3a(): void
     {
-        if ( ($position = $this->search(array('heid'))) !== false) {
-            if ($this->inR2($position)) {
-                $letter = UTF8::substr($this->word, -5, 1);
-                if ($letter !== 'c') {
-                    $this->word = UTF8::substr($this->word, 0, $position);
+        if ($position = $this->search(['heid']) !== false && $this->inR2($position)) {
+            $letter = UTF8::substr($this->word, -5, 1);
+            if ($letter !== 'c') {
+                $this->word = UTF8::substr($this->word, 0, $position);
 
-                    if ( ($position = $this->search(array('en'))) !== false) {
-                        if ($this->inR1($position)) {
-                            $word = UTF8::substr($this->word, 0, $position);
-                            if ($this->hasValidEnEnding($word)) {
-                                $this->word = $word;
-                                $this->unDoubling();
-                            }
-                        }
+                if ($position = $this->search(['en']) !== false && $this->inR1($position)) {
+                    $word = UTF8::substr($this->word, 0, $position);
+                    if ($this->hasValidEnEnding($word)) {
+                        $this->word = $word;
+                        $this->unDoubling();
                     }
                 }
             }
@@ -199,16 +189,16 @@ private function step3a()
      * Step 3b: d-suffixe
      * Search for the longest among the following suffixes, and perform the action indicated.
      */
-    private function step3b($removedE)
+    private function step3b($removedE): bool
     {
         // end   ing
         //      delete if in R2
         //      if preceded by ig, delete if in R2 and not preceded by e, otherwise undouble the ending
-        if ( ($position = $this->search(array('end', 'ing'))) !== false) {
+        if ( ($position = $this->search(['end', 'ing'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
-                if ( ($position2 = $this->searchIfInR2(array('ig'))) !== false) {
+                if ( ($position2 = $this->searchIfInR2(['ig'])) !== false) {
                     $letter = UTF8::substr($this->word, -3, 1);
                     if ($letter !== 'e') {
                         $this->word = UTF8::substr($this->word, 0, $position2);
@@ -224,7 +214,7 @@ private function step3b($removedE)
 
         // ig
         //      delete if in R2 and not preceded by e
-        if ( ($position = $this->search(array('ig'))) !== false) {
+        if ( ($position = $this->search(['ig'])) !== false) {
             if ($this->inR2($position)) {
                 $letter = UTF8::substr($this->word, -3, 1);
                 if ($letter !== 'e') {
@@ -236,7 +226,7 @@ private function step3b($removedE)
 
         // lijk
         //      delete if in R2, and then repeat step 2
-        if ( ($position = $this->search(array('lijk'))) !== false) {
+        if ( ($position = $this->search(['lijk'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
                 $this->step2();
@@ -246,7 +236,7 @@ private function step3b($removedE)
 
         // baar
         //      delete if in R2
-        if ( ($position = $this->search(array('baar'))) !== false) {
+        if ( ($position = $this->search(['baar'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -255,7 +245,7 @@ private function step3b($removedE)
 
         // bar
         //      delete if in R2 and if step 2 actually removed an e
-        if ( ($position = $this->search(array('bar'))) !== false) {
+        if ( ($position = $this->search(['bar'])) !== false) {
             if ($this->inR2($position) && $removedE) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -270,17 +260,17 @@ private function step3b($removedE)
      * If the words ends CVD, where C is a non-vowel, D is a non-vowel other than I, and V is double a, e, o or u,
      * remove one of the vowels from V (for example, maan -> man, brood -> brod).
      */
-    private function step4()
+    private function step4(): ?bool
     {
         // D is a non-vowel other than I
         $d = UTF8::substr($this->word, -1, 1);
-        if (in_array($d, array_merge(self::$vowels, array('I')))) {
+        if (in_array($d, array_merge(self::$vowels, ['I']))) {
             return false;
         }
 
         // V is double a, e, o or u
         $v = UTF8::substr($this->word, -3, 2);
-        if (!in_array($v, array('aa', 'ee', 'oo', 'uu'))) {
+        if (!in_array($v, ['aa', 'ee', 'oo', 'uu'])) {
             return false;
         }
         $singleV = UTF8::substr($v, 0, 1);
@@ -293,14 +283,15 @@ private function step4()
 
         $this->word = UTF8::substr($this->word, 0, -4);
         $this->word .= $c . $singleV  .$d;
+        return null;
     }
 
     /**
      * Finally
      * Turn I and Y back into lower case.
      */
-    private function finish()
+    private function finish(): void
     {
-        $this->word = str_replace(array('I', 'Y'), array('i', 'y'), $this->word);
+        $this->word = str_replace(['I', 'Y'], ['i', 'y'], $this->word);
     }
 }
diff --git a/src/Stemmer/English.php b/src/Stemmer/English.php
index 0e747d0..b7e4c40 100644
--- a/src/Stemmer/English.php
+++ b/src/Stemmer/English.php
@@ -16,11 +16,11 @@ class English extends Stem
     /**
      * All english vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y'];
 
-    protected static $doubles = array('bb', 'dd', 'ff', 'gg', 'mm', 'nn', 'pp', 'rr', 'tt');
+    protected static $doubles = ['bb', 'dd', 'ff', 'gg', 'mm', 'nn', 'pp', 'rr', 'tt'];
 
-    protected static $liEnding = array('c', 'd', 'e', 'g', 'h', 'k', 'm', 'n', 'r', 't');
+    protected static $liEnding = ['c', 'd', 'e', 'g', 'h', 'k', 'm', 'n', 'r', 't'];
 
     /**
      * {@inheritdoc}
@@ -85,25 +85,25 @@ public function stem($word)
      * Step 0
      * Remove ', 's, 's'
      */
-    private function step0()
+    private function step0(): void
     {
-        if ( ($position = $this->search(array("'s'", "'s", "'"))) !== false) {
+        if ( ($position = $this->search(["'s'", "'s", "'"])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
         }
     }
 
-    private function step1a()
+    private function step1a(): bool
     {
         // sses
         //      replace by ss
-        if ( ($position = $this->search(array('sses'))) !== false) {
+        if ( ($position = $this->search(['sses'])) !== false) {
             $this->word = preg_replace('#(sses)$#u', 'ss', $this->word);
             return true;
         }
 
         // ied+   ies*
         //      replace by i if preceded by more than one letter, otherwise by ie (so ties -> tie, cries -> cri)
-        if ( ($position = $this->search(array('ied', 'ies'))) !== false) {
+        if ( ($position = $this->search(['ied', 'ies'])) !== false) {
             if ($position > 1) {
                 $this->word = preg_replace('#(ied|ies)$#u', 'i', $this->word);
 
@@ -115,13 +115,13 @@ private function step1a()
 
         // us+   ss
         //  do nothing
-        if ( ($position = $this->search(array('us', 'ss'))) !== false) {
+        if ( ($position = $this->search(['us', 'ss'])) !== false) {
             return true;
         }
 
         // s
         //      delete if the preceding word part contains a vowel not immediately before the s (so gas and this retain the s, gaps and kiwis lose it)
-        if ( ($position = $this->search(array('s'))) !== false) {
+        if ( ($position = $this->search(['s'])) !== false) {
             for ($i=0; $i<$position-1; $i++) {
                 $letter = UTF8::substr($this->word, $i, 1);
 
@@ -139,11 +139,11 @@ private function step1a()
     /**
      * Step 1b
      */
-    private function step1b()
+    private function step1b(): bool
     {
         // eed   eedly+
         //      replace by ee if in R1
-        if ( ($position = $this->search(array('eedly', 'eed'))) !== false) {
+        if ( ($position = $this->search(['eedly', 'eed'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(eedly|eed)$#u', 'ee', $this->word);
             }
@@ -155,14 +155,14 @@ private function step1b()
         //      if the word ends at, bl or iz add e (so luxuriat -> luxuriate), or
         //      if the word ends with a double remove the last letter (so hopp -> hop), or
         //      if the word is short, add e (so hop -> hope)
-        if ( ($position = $this->search(array('edly', 'ingly', 'ed', 'ing'))) !== false) {
+        if ( ($position = $this->search(['edly', 'ingly', 'ed', 'ing'])) !== false) {
             for ($i=0; $i<$position; $i++) {
                 $letter = UTF8::substr($this->word, $i, 1);
 
                 if (in_array($letter, self::$vowels)) {
                     $this->word = UTF8::substr($this->word, 0, $position);
 
-                    if ($this->search(array('at', 'bl', 'iz')) !== false) {
+                    if ($this->search(['at', 'bl', 'iz']) !== false) {
                         $this->word .= 'e';
 
                     } elseif ( ($position2 = $this->search(self::$doubles)) !== false) {
@@ -184,7 +184,7 @@ private function step1b()
     /**
      * Step 1c: *
      */
-    private function step1c()
+    private function step1c(): bool
     {
         // replace suffix y or Y by i if preceded by a non-vowel
         // which is not the first letter of the word (so cry -> cri, by -> by, say -> say)
@@ -194,7 +194,7 @@ private function step1c()
             return true;
         }
 
-        if ( ($position = $this->search(array('y', 'Y'))) !== false) {
+        if ( ($position = $this->search(['y', 'Y'])) !== false) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
 
@@ -212,10 +212,10 @@ private function step1c()
      * Step 2
      *  Search for the longest among the following suffixes, and, if found and in R1, perform the action indicated.
      */
-    private function step2()
+    private function step2(): bool
     {
         // iveness   iviti:   replace by ive
-        if ( ($position = $this->search(array('iveness', 'iviti'))) !== false) {
+        if ( ($position = $this->search(['iveness', 'iviti'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(iveness|iviti)$#u', 'ive', $this->word);
             }
@@ -223,7 +223,7 @@ private function step2()
         }
 
         // ousli   ousness:   replace by ous
-        if ( ($position = $this->search(array('ousli', 'ousness'))) !== false) {
+        if ( ($position = $this->search(['ousli', 'ousness'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ousli|ousness)$#u', 'ous', $this->word);
             }
@@ -231,7 +231,7 @@ private function step2()
         }
 
         // izer   ization:   replace by ize
-        if ( ($position = $this->search(array('izer', 'ization'))) !== false) {
+        if ( ($position = $this->search(['izer', 'ization'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(izer|ization)$#u', 'ize', $this->word);
             }
@@ -239,7 +239,7 @@ private function step2()
         }
 
         // ational   ation   ator:   replace by ate
-        if ( ($position = $this->search(array('ational', 'ation', 'ator'))) !== false) {
+        if ( ($position = $this->search(['ational', 'ation', 'ator'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ational|ation|ator)$#u', 'ate', $this->word);
             }
@@ -247,7 +247,7 @@ private function step2()
         }
 
         // biliti   bli+:   replace by ble
-        if ( ($position = $this->search(array('biliti', 'bli'))) !== false) {
+        if ( ($position = $this->search(['biliti', 'bli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(biliti|bli)$#u', 'ble', $this->word);
             }
@@ -255,7 +255,7 @@ private function step2()
         }
 
         // lessli+:   replace by less
-        if ( ($position = $this->search(array('lessli'))) !== false) {
+        if ( ($position = $this->search(['lessli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(lessli)$#u', 'less', $this->word);
             }
@@ -263,7 +263,7 @@ private function step2()
         }
 
         // fulness:   replace by ful
-        if ( ($position = $this->search(array('fulness', 'fulli'))) !== false) {
+        if ( ($position = $this->search(['fulness', 'fulli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(fulness|fulli)$#u', 'ful', $this->word);
             }
@@ -271,7 +271,7 @@ private function step2()
         }
 
         // tional:   replace by tion
-        if ( ($position = $this->search(array('tional'))) !== false) {
+        if ( ($position = $this->search(['tional'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(tional)$#u', 'tion', $this->word);
             }
@@ -279,7 +279,7 @@ private function step2()
         }
 
         // alism   aliti   alli:   replace by al
-        if ( ($position = $this->search(array('alism', 'aliti', 'alli'))) !== false) {
+        if ( ($position = $this->search(['alism', 'aliti', 'alli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(alism|aliti|alli)$#u', 'al', $this->word);
             }
@@ -287,7 +287,7 @@ private function step2()
         }
 
         // enci:   replace by ence
-        if ( ($position = $this->search(array('enci'))) !== false) {
+        if ( ($position = $this->search(['enci'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(enci)$#u', 'ence', $this->word);
             }
@@ -295,7 +295,7 @@ private function step2()
         }
 
         // anci:   replace by ance
-        if ( ($position = $this->search(array('anci'))) !== false) {
+        if ( ($position = $this->search(['anci'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(anci)$#u', 'ance', $this->word);
             }
@@ -303,7 +303,7 @@ private function step2()
         }
 
         // abli:   replace by able
-        if ( ($position = $this->search(array('abli'))) !== false) {
+        if ( ($position = $this->search(['abli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(abli)$#u', 'able', $this->word);
             }
@@ -311,7 +311,7 @@ private function step2()
         }
 
         // entli:   replace by ent
-        if ( ($position = $this->search(array('entli'))) !== false) {
+        if ( ($position = $this->search(['entli'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(entli)$#u', 'ent', $this->word);
             }
@@ -319,7 +319,7 @@ private function step2()
         }
 
         // ogi+:   replace by og if preceded by l
-        if ( ($position = $this->search(array('ogi'))) !== false) {
+        if ( ($position = $this->search(['ogi'])) !== false) {
 
             if ($this->inR1($position)) {
                 $before = $position - 1;
@@ -334,7 +334,7 @@ private function step2()
         }
 
         // li+:   delete if preceded by a valid li-ending
-        if ( ($position = $this->search(array('li'))) !== false) {
+        if ( ($position = $this->search(['li'])) !== false) {
 
             if ($this->inR1($position)) {
                 // a letter for you
@@ -355,40 +355,40 @@ private function step2()
      * Step 3:
      * Search for the longest among the following suffixes, and, if found and in R1, perform the action indicated.
      */
-    private function step3()
+    private function step3(): bool
     {
         // ational+:   replace by ate
-        if ($this->searchIfInR1(array('ational')) !== false) {
+        if ($this->searchIfInR1(['ational']) !== false) {
             $this->word = preg_replace('#(ational)$#u', 'ate', $this->word);
             return true;
         }
 
         // tional+:   replace by tion
-        if ($this->searchIfInR1(array('tional')) !== false) {
+        if ($this->searchIfInR1(['tional']) !== false) {
             $this->word = preg_replace('#(tional)$#u', 'tion', $this->word);
             return true;
         }
 
         // alize:   replace by al
-        if ($this->searchIfInR1(array('alize')) !== false) {
+        if ($this->searchIfInR1(['alize']) !== false) {
             $this->word = preg_replace('#(alize)$#u', 'al', $this->word);
             return true;
         }
 
         // icate   iciti   ical:   replace by ic
-        if ($this->searchIfInR1(array('icate', 'iciti', 'ical')) !== false) {
+        if ($this->searchIfInR1(['icate', 'iciti', 'ical']) !== false) {
             $this->word = preg_replace('#(icate|iciti|ical)$#u', 'ic', $this->word);
             return true;
         }
 
         // ful   ness:   delete
-        if ( ($position = $this->searchIfInR1(array('ful', 'ness'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['ful', 'ness'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         // ative*:   delete if in R2
-        if ( (($position = $this->searchIfInR1(array('ative'))) !== false) && ($this->inR2($position)) )  {
+        if ( (($position = $this->searchIfInR1(['ative'])) !== false) && ($this->inR2($position)) )  {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
@@ -400,13 +400,13 @@ private function step3()
      * Step 4
      * Search for the longest among the following suffixes, and, if found and in R2, perform the action indicated.
      */
-    private function step4()
+    private function step4(): bool
     {
         //    ement  ance   ence  able ible   ant  ment   ent   ism   ate   iti   ous   ive   ize al  er   ic
         //      delete
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'ance', 'ence', 'ement', 'able', 'ible', 'ant', 'ment', 'ent', 'ism',
-            'ate', 'iti', 'ous', 'ive', 'ize', 'al', 'er', 'ic'))) !== false) {
+            'ate', 'iti', 'ous', 'ive', 'ize', 'al', 'er', 'ic'])) !== false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
@@ -416,7 +416,7 @@ private function step4()
 
         // ion
         //      delete if preceded by s or t
-        if ( ($position = $this->searchIfInR2(array('ion'))) !== false) {
+        if ( ($position = $this->searchIfInR2(['ion'])) !== false) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
 
@@ -434,11 +434,11 @@ private function step4()
      * Step 5: *
      * Search for the the following suffixes, and, if found, perform the action indicated.
      */
-    private function step5()
+    private function step5(): bool
     {
         // e
         //      delete if in R2, or in R1 and not preceded by a short syllable
-        if ( ($position = $this->search(array('e'))) !== false) {
+        if ( ($position = $this->search(['e'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
@@ -453,7 +453,7 @@ private function step5()
 
         // l
         //      delete if in R2 and preceded by l
-        if ( ($position = $this->searchIfInR2(array('l'))) !== false) {
+        if ( ($position = $this->searchIfInR2(['l'])) !== false) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
 
@@ -467,12 +467,12 @@ private function step5()
         return false;
     }
 
-    private function finish()
+    private function finish(): void
     {
         $this->word = str_replace('Y', 'y', $this->word);
     }
 
-    private function exceptionR1()
+    private function exceptionR1(): void
     {
         if (Utf8::strpos($this->word, 'gener') === 0) {
             $this->r1 = UTF8::substr($this->word, 5);
@@ -492,9 +492,9 @@ private function exceptionR1()
      *  1/ Stem certain special words as follows,
      *  2/ If one of the following is found, leave it invariant,
      */
-    private function exception1()
+    private function exception1(): ?string
     {
-        $exceptions = array(
+        $exceptions = [
             'skis'   => 'ski',
             'skies'  => 'sky',
             'dying'  => 'die',
@@ -514,21 +514,17 @@ private function exception1()
             'cosmos' => 'cosmos',
             'bias'   => 'bias',
             'andes'  => 'andes'
-        );
+        ];
 
-        if (isset($exceptions[$this->word])) {
-            return $exceptions[$this->word];
-        }
-
-        return null;
+        return $exceptions[$this->word] ?? null;
     }
 
     /**
      * Following step 1a, leave the following invariant,
      */
-    private function exception2()
+    private function exception2(): ?string
     {
-        $exceptions = array(
+        $exceptions = [
             'inning' => 'inning',
             'outing' => 'outing',
             'canning' => 'canning',
@@ -537,22 +533,16 @@ private function exception2()
             'proceed' => 'proceed',
             'exceed'  => 'exceed',
             'succeed' => 'succeed'
-        );
-
-        if (isset($exceptions[$this->word])) {
-            return $exceptions[$this->word];
-        }
+        ];
 
-        return null;
+        return $exceptions[$this->word] ?? null;
     }
 
     /**
      *  A word is called short if it ends in a short syllable, and if R1 is null.
      *  Note : R1 not really null, but the word at this state must be smaller than r1 index
-     *
-     *  @return boolean
      */
-    private function isShort()
+    private function isShort(): bool
     {
         $length = UTF8::strlen($this->word);
         return ( ($this->searchShortSyllabe(-3, 3) || $this->searchShortSyllabe(-2, 2)) && ($length == $this->r1Index) );
@@ -565,7 +555,7 @@ private function isShort()
      *  So rap, trap, entrap end with a short syllable, and ow, on, at are classed as short syllables.
      *  But uproot, bestow, disturb do not end with a short syllable.
      */
-    private function searchShortSyllabe($from, $nbLetters)
+    private function searchShortSyllabe(int $from, int $nbLetters)
     {
         $length = UTF8::strlen($this->word);
 
@@ -577,26 +567,19 @@ private function searchShortSyllabe($from, $nbLetters)
         }
 
         // (a) is just for beginning of the word
-        if ( ($nbLetters == 2) && ($from != 0) ) {
+        if ( ($nbLetters === 2) && ($from != 0) ) {
             return false;
         }
 
         $first = UTF8::substr($this->word, $from, 1);
         $second = UTF8::substr($this->word, ($from+1), 1);
 
-        if ($nbLetters == 2) {
-            if ( (in_array($first, self::$vowels)) && (!in_array($second, self::$vowels)) ) {
-                return true;
-            }
+        if ($nbLetters === 2 && (in_array($first, self::$vowels) && !in_array($second, self::$vowels))) {
+            return true;
         }
 
         $third = UTF8::substr($this->word, ($from+2), 1);
-
-        if ( (!in_array($first, self::$vowels)) && (in_array($second, self::$vowels))
-            && (!in_array($third, array_merge(self::$vowels, array('x', 'Y', 'w'))))) {
-                return true;
-            }
-
-        return false;
+        return (!in_array($first, self::$vowels)) && (in_array($second, self::$vowels))
+            && (!in_array($third, array_merge(self::$vowels, ['x', 'Y', 'w'])));
     }
 }
diff --git a/src/Stemmer/Finnish.php b/src/Stemmer/Finnish.php
index 25539b2..6a8f749 100644
--- a/src/Stemmer/Finnish.php
+++ b/src/Stemmer/Finnish.php
@@ -19,24 +19,24 @@ class Finnish extends Stem
     /**
      * All swedish vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'ä', 'ö');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'ä', 'ö'];
 
-    protected static $consonants = array('b', 'c', 'd', 'f', 'g', 'h', 'j',
-    'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'v', 'w', 'x', 'z');
+    protected static $consonants = ['b', 'c', 'd', 'f', 'g', 'h', 'j',
+    'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'v', 'w', 'x', 'z'];
 
-    protected static $restrictedVowels = array('a', 'e', 'i', 'o', 'u', 'ä', 'ö');
+    protected static $restrictedVowels = ['a', 'e', 'i', 'o', 'u', 'ä', 'ö'];
 
     /**
      * Long restricted vowels, ie. doubled vowels.
      */
-    protected static $longVowels = array('aa', 'ee', 'ii', 'oo', 'uu', 'ää', 'öö');
+    protected static $longVowels = ['aa', 'ee', 'ii', 'oo', 'uu', 'ää', 'öö'];
 
     private $_removedInStep3 = false;
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (! UTF8::is_utf8($word)) {
@@ -69,11 +69,11 @@ public function stem($word)
      *
      * @return boolean True when something is done.
      */
-    private function step1()
+    private function step1(): ?bool
     {
         // (a) kin   kaan   kään   ko   kö   han   hän   pa   pä
         //      delete if preceded by n, t or a vowel
-        if (($position = $this->searchIfInR1(array('kaan', 'kään', 'kin', 'han', 'hän', 'ko', 'kö', 'pa', 'pä'))) !== false) {
+        if (($position = $this->searchIfInR1(['kaan', 'kään', 'kin', 'han', 'hän', 'ko', 'kö', 'pa', 'pä'])) !== false) {
             $lastLetter = Utf8::substr($this->word, ($position-1), 1);
 
             if (in_array($lastLetter, array_merge(['t', 'n'], self::$vowels))) {
@@ -87,7 +87,7 @@ private function step1()
 
         //  sti
         //  delete if in R2
-        if (($position = $this->searchIfInR1(array('sti'))) !== false) {
+        if (($position = $this->searchIfInR1(['sti'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = Utf8::substr($this->word, 0, $position);
                 $this->r1();
@@ -96,6 +96,7 @@ private function step1()
 
             return true;
         }
+        return null;
     }
 
     /**
@@ -106,11 +107,11 @@ private function step1()
      *
      * @return boolean True when something is done.
      */
-    private function step2()
+    private function step2(): ?bool
     {
         // si
         //  delete if not preceded by k
-        if (($position = $this->searchIfInR1(array('si'))) !== false) {
+        if (($position = $this->searchIfInR1(['si'])) !== false) {
             $lastLetter = Utf8::substr($this->word, ($position-1), 1);
 
             if ($lastLetter !== 'k') {
@@ -123,10 +124,10 @@ private function step2()
 
         // ni
         //  delete
-        if (($position = $this->searchIfInR1(array('ni'))) !== false) {
+        if (($position = $this->searchIfInR1(['ni'])) !== false) {
             $this->word = Utf8::substr($this->word, 0, $position);
             // if preceded by kse, replace with ksi
-            if ( ($position = $this->search(array('kse'))) !== false) {
+            if ( ($position = $this->search(['kse'])) !== false) {
                 $this->word = preg_replace('#(kse)$#u', 'ksi', $this->word);
             }
             $this->r1();
@@ -136,7 +137,7 @@ private function step2()
 
         // nsa   nsä   mme   nne
         //  delete
-        if (($position = $this->searchIfInR1(array('nsa', 'nsä', 'mme', 'nne'))) !== false) {
+        if (($position = $this->searchIfInR1(['nsa', 'nsä', 'mme', 'nne'])) !== false) {
             $this->word = Utf8::substr($this->word, 0, $position);
             $this->r1();
             $this->r2();
@@ -145,11 +146,11 @@ private function step2()
 
         // an
         //  delete if preceded by one of   ta   ssa   sta   lla   lta   na
-        if (($position = $this->searchIfInR1(array('an'))) !== false) {
+        if (($position = $this->searchIfInR1(['an'])) !== false) {
             $word = Utf8::substr($this->word, 0, $position);
             $lastThreeLetters = Utf8::substr($word, -3, 3);
             $lastTwoLetters = Utf8::substr($word, -2, 2);
-            if (in_array($lastThreeLetters, array('ssa', 'sta', 'lla', 'lta'), true) || in_array($lastTwoLetters, array('na', 'ta'), true)) {
+            if (in_array($lastThreeLetters, ['ssa', 'sta', 'lla', 'lta'], true) || in_array($lastTwoLetters, ['na', 'ta'], true)) {
                 $this->word = $word;
                 $this->r1();
                 $this->r2();
@@ -159,11 +160,11 @@ private function step2()
 
         // än
         // delete if preceded by one of   tä   ssä   stä   llä   ltä   nä
-        if (($position = $this->searchIfInR1(array('än'))) !== false) {
+        if (($position = $this->searchIfInR1(['än'])) !== false) {
             $word = Utf8::substr($this->word, 0, $position);
             $lastThreeLetters = Utf8::substr($word, -3, 3);
             $lastTwoLetters = Utf8::substr($word, -2, 2);
-            if (in_array($lastThreeLetters, array('ssä', 'stä', 'llä', 'ltä'), true) || in_array($lastTwoLetters, array('nä', 'tä'), true)) {
+            if (in_array($lastThreeLetters, ['ssä', 'stä', 'llä', 'ltä'], true) || in_array($lastTwoLetters, ['nä', 'tä'], true)) {
                 $this->word = $word;
                 $this->r1();
                 $this->r2();
@@ -173,11 +174,11 @@ private function step2()
 
         // en
         // delete if preceded by one of   lle   ine
-        if (($position = $this->searchIfInR1(array('en'))) !== false) {
+        if (($position = $this->searchIfInR1(['en'])) !== false) {
             $word = Utf8::substr($this->word, 0, $position);
             if (Utf8::strlen($this->word) > 4) {
                 $lastThreeLetters = Utf8::substr($this->word, -5, 3);
-                if (in_array($lastThreeLetters, array('lle', 'ine'), true)) {
+                if (in_array($lastThreeLetters, ['lle', 'ine'], true)) {
                     $this->word = $word;
                     $this->r1();
                     $this->r2();
@@ -185,6 +186,7 @@ private function step2()
                 }
             }
         }
+        return null;
     }
 
     /**
@@ -195,7 +197,7 @@ private function step2()
      *
      * @return boolean True when something is done.
      */
-    private function step3()
+    private function step3(): ?bool
     {
         // hXn
         // delete if preceded by X, where X is a V other than u (a/han, e/hen etc)
@@ -203,7 +205,7 @@ private function step3()
             if ($vowel === 'u') {
                 continue;
             }
-            if (($position = $this->searchIfInR1(array('h' . $vowel . 'n'))) !== false) {
+            if (($position = $this->searchIfInR1(['h' . $vowel . 'n'])) !== false) {
                 $lastLetter = Utf8::substr($this->word, $position-1, 1);
                 if ($lastLetter === $vowel) {
                     $this->word = Utf8::substr($this->word, 0, $position);
@@ -217,7 +219,7 @@ private function step3()
 
         // siin   den   tten
         // delete if preceded by Vi
-        if (($position = $this->searchIfInR1(array('siin', 'den', 'tten'))) !== false) {
+        if (($position = $this->searchIfInR1(['siin', 'den', 'tten'])) !== false) {
             $lastLetter = Utf8::substr($this->word, ($position-1), 1);
             if ($lastLetter === 'i') {
                 $nextLastLetter = Utf8::substr($this->word, ($position-2), 1);
@@ -233,7 +235,7 @@ private function step3()
 
         // seen
         // delete if preceded by LV
-        if (($position = $this->searchIfInR1(array('seen'))) !== false) {
+        if (($position = $this->searchIfInR1(['seen'])) !== false) {
             $lastLetters = Utf8::substr($this->word, ($position-2), 2);
 
             if (in_array($lastLetters, self::$longVowels, true)) {
@@ -247,7 +249,7 @@ private function step3()
 
         // tta    ttä
         // delete if preceded by e
-        if (($position = $this->searchIfInR1(array('tta', 'ttä'))) !== false) {
+        if (($position = $this->searchIfInR1(['tta', 'ttä'])) !== false) {
             $lastLetter = Utf8::substr($this->word, ($position-1), 1);
 
             if ($lastLetter === 'e') {
@@ -261,7 +263,7 @@ private function step3()
 
         // ta  tä  ssa  ssä  sta  stä  lla  llä  lta  ltä  lle  na  nä  ksi  ine
         // delete
-        if (($position = $this->searchIfInR1(array('ssa', 'ssä', 'sta', 'stä', 'lla', 'llä', 'lta', 'ltä', 'lle', 'ksi', 'na', 'nä', 'ine', 'ta', 'tä'))) !== false) {
+        if (($position = $this->searchIfInR1(['ssa', 'ssä', 'sta', 'stä', 'lla', 'llä', 'lta', 'ltä', 'lle', 'ksi', 'na', 'nä', 'ine', 'ta', 'tä'])) !== false) {
             $this->word = Utf8::substr($this->word, 0, $position);
             $this->_removedInStep3 = true;
             $this->r1();
@@ -271,7 +273,7 @@ private function step3()
 
         // a    ä
         // delete if preceded by cv
-        if (($position = $this->searchIfInR1(array('a', 'ä'))) !== false) {
+        if (($position = $this->searchIfInR1(['a', 'ä'])) !== false) {
             $lastLetter = Utf8::substr($this->word, ($position-1), 1);
             $nextLastLetter = Utf8::substr($this->word, ($position-2), 1);
 
@@ -286,7 +288,7 @@ private function step3()
 
         // n
         // delete, and if preceded by LV or ie, delete the last vowel
-        if (($position = $this->searchIfInR1(array('n'))) !== false) {
+        if (($position = $this->searchIfInR1(['n'])) !== false) {
             $lastLetters = Utf8::substr($this->word, ($position-2), 2);
 
             if (in_array($lastLetters, self::$longVowels, true) || $lastLetters === 'ie') {
@@ -299,6 +301,7 @@ private function step3()
             $this->_removedInStep3 = true;
             return true;
         }
+        return null;
     }
 
     /**
@@ -309,11 +312,11 @@ private function step3()
      *
      * @return boolean True when something is done.
      */
-    private function step4()
+    private function step4(): ?bool
     {
         // mpi   mpa   mpä   mmi   mma   mmä
         // delete if not preceded by po
-        if (($position = $this->searchIfInR2(array('mpi', 'mpa', 'mpä', 'mmi', 'mma', 'mmä'))) !== false) {
+        if (($position = $this->searchIfInR2(['mpi', 'mpa', 'mpä', 'mmi', 'mma', 'mmä'])) !== false) {
             $lastLetters = Utf8::substr($this->word, ($position-2), 2);
             if ($lastLetters !== 'po') {
                 $this->word = Utf8::substr($this->word, 0, $position);
@@ -325,12 +328,13 @@ private function step4()
 
         // impi   impa   impä   immi   imma   immä   eja   ejä
         // delete
-        if (($position = $this->searchIfInR2(array('impi', 'impa', 'impä', 'immi', 'imma', 'immä', 'eja', 'ejä'))) !== false) {
+        if (($position = $this->searchIfInR2(['impi', 'impa', 'impä', 'immi', 'imma', 'immä', 'eja', 'ejä'])) !== false) {
             $this->word = Utf8::substr($this->word, 0, $position);
             $this->r1();
             $this->r2();
             return true;
         }
+        return null;
     }
 
     /**
@@ -343,39 +347,38 @@ private function step4()
      *
      * @return boolean True when something is done.
      */
-    private function step5()
+    private function step5(): ?bool
     {
         if ($this->_removedInStep3) {
-            if (($position = $this->searchIfInR1(array('i', 'j'))) !== false) {
+            if (($position = $this->searchIfInR1(['i', 'j'])) !== false) {
                 $this->word = Utf8::substr($this->word, 0, $position);
                 $this->r1();
                 $this->r2();
                 return true;
             }
-        } else {
-            if (($position = $this->searchIfInR1(array('t'))) !== false) {
-                $lastLetter = Utf8::substr($this->word, ($position-1), 1);
-                if (in_array($lastLetter, self::$vowels, true)) {
-                    $this->word = Utf8::substr($this->word, 0, $position);
+        } elseif (($position = $this->searchIfInR1(['t'])) !== false) {
+            $lastLetter = Utf8::substr($this->word, ($position-1), 1);
+            if (in_array($lastLetter, self::$vowels, true)) {
+                $this->word = Utf8::substr($this->word, 0, $position);
+                $this->r1();
+                $this->r2();
+                if (($position2 = $this->searchIfInR2(['imma'])) !== false) {
+                    $this->word = Utf8::substr($this->word, 0, $position2);
                     $this->r1();
                     $this->r2();
-                    if (($position2 = $this->searchIfInR2(array('imma'))) !== false) {
+                    return true;
+                } elseif (($position2 = $this->searchIfInR2(['mma'])) !== false) {
+                    $lastLetters = Utf8::substr($this->word, ($position2-2), 2);
+                    if ($lastLetters !== 'po') {
                         $this->word = Utf8::substr($this->word, 0, $position2);
                         $this->r1();
                         $this->r2();
                         return true;
-                    } elseif (($position2 = $this->searchIfInR2(array('mma'))) !== false) {
-                        $lastLetters = Utf8::substr($this->word, ($position2-2), 2);
-                        if ($lastLetters !== 'po') {
-                            $this->word = Utf8::substr($this->word, 0, $position2);
-                            $this->r1();
-                            $this->r2();
-                            return true;
-                        }
                     }
                 }
             }
         }
+        return null;
 
     }
 
@@ -385,7 +388,7 @@ private function step5()
      * Do in turn steps (a), (b), (c), (d), restricting all tests to the
      * region R1.
      */
-    private function step6()
+    private function step6(): void
     {
         // a) If R1 ends LV
         // delete the last letter
@@ -399,7 +402,7 @@ private function step6()
         // delete the last letter
         $lastLetter = Utf8::substr($this->r1, -1, 1);
         $secondToLastLetter = Utf8::substr($this->r1, -2, 1);
-        if (in_array($secondToLastLetter, self::$consonants, true) && in_array($lastLetter, array('a', 'e', 'i', 'ä'))) {
+        if (in_array($secondToLastLetter, self::$consonants, true) && in_array($lastLetter, ['a', 'e', 'i', 'ä'])) {
             $this->word = Utf8::substr($this->word, 0, -1);
             $this->r1();
             $this->r2();
@@ -408,7 +411,7 @@ private function step6()
         // c) If R1 ends oj or uj
         // delete the last letter
         $twoLastLetters = Utf8::substr($this->r1, -2, 2);
-        if (in_array($twoLastLetters, array('oj', 'uj'))) {
+        if (in_array($twoLastLetters, ['oj', 'uj'])) {
             $this->word = Utf8::substr($this->word, 0, -1);
             $this->r1();
             $this->r2();
diff --git a/src/Stemmer/French.php b/src/Stemmer/French.php
index cef305e..f32fafa 100644
--- a/src/Stemmer/French.php
+++ b/src/Stemmer/French.php
@@ -15,12 +15,12 @@ class French extends Stem
     /**
      * All french vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'â', 'à', 'ë', 'é', 'ê', 'è', 'ï', 'î', 'ô', 'û', 'ù');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'â', 'à', 'ë', 'é', 'ê', 'è', 'ï', 'î', 'ô', 'û', 'ù'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -43,14 +43,14 @@ public function stem($word)
         $nextStep = $this->step1();
 
         // Do step 2a if either no ending was removed by step 1, or if one of endings amment, emment, ment, ments was found.
-        if ( ($nextStep == 2) || ($this->originalWord == $this->word) ) {
+        if ( ($nextStep == 2) || ($this->originalWord === $this->word) ) {
             $modified = $this->step2a();
             if (!$modified) {
                 $this->step2b();
             }
         }
 
-        if ($this->word != $this->originalWord) {
+        if ($this->word !== $this->originalWord) {
             $this->step3();
 
         } else {
@@ -75,7 +75,7 @@ public function stem($word)
      *      yeux 		-> 		Yeux
      *      quand 		-> 		qUand
      */
-    private function step0()
+    private function step0(): void
     {
         $this->word = preg_replace('#([q])u#u', '$1U', $this->word);
         $this->word = preg_replace('#(['.$this->plainVowels.'])y#u', '$1Y', $this->word);
@@ -90,11 +90,11 @@ private function step0()
      *
      * @return integer Next step number
      */
-    private function step1()
+    private function step1(): int
     {
         // ance   iqUe   isme   able   iste   eux   ances   iqUes   ismes   ables   istes
         //     delete if in R2
-        if ( ($position = $this->search(array('ances', 'iqUes', 'ismes', 'ables', 'istes', 'ance', 'iqUe','isme', 'able', 'iste', 'eux'))) !== false) {
+        if ( ($position = $this->search(['ances', 'iqUes', 'ismes', 'ables', 'istes', 'ance', 'iqUe','isme', 'able', 'iste', 'eux'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -104,11 +104,11 @@ private function step1()
         // atrice   ateur   ation   atrices   ateurs   ations
         //      delete if in R2
         //      if preceded by ic, delete if in R2, else replace by iqU
-        if ( ($position = $this->search(array('atrices', 'ateurs', 'ations', 'atrice', 'ateur', 'ation'))) !== false) {
+        if ( ($position = $this->search(['atrices', 'ateurs', 'ations', 'atrice', 'ateur', 'ation'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
-                if ( ($position2 = $this->searchIfInR2(array('ic'))) !== false) {
+                if ( ($position2 = $this->searchIfInR2(['ic'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position2);
                 } else {
                     $this->word = preg_replace('#(ic)$#u', 'iqU', $this->word);
@@ -120,7 +120,7 @@ private function step1()
 
         // logie   logies
         //      replace with log if in R2
-        if ( ($position = $this->search(array('logies', 'logie'))) !== false) {
+        if ( ($position = $this->search(['logies', 'logie'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(logies|logie)$#u', 'log', $this->word);
             }
@@ -129,7 +129,7 @@ private function step1()
 
         // usion   ution   usions   utions
         //      replace with u if in R2
-        if ( ($position = $this->search(array('usions', 'utions', 'usion', 'ution'))) !== false) {
+        if ( ($position = $this->search(['usions', 'utions', 'usion', 'ution'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(usion|ution|usions|utions)$#u', 'u', $this->word);
             }
@@ -138,7 +138,7 @@ private function step1()
 
         // ence   ences
         //      replace with ent if in R2
-        if ( ($position = $this->search(array('ences', 'ence'))) !== false) {
+        if ( ($position = $this->search(['ences', 'ence'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(ence|ences)$#u', 'ent', $this->word);
             }
@@ -147,7 +147,7 @@ private function step1()
 
         // issement   issements
         //      delete if in R1 and preceded by a non-vowel
-        if ( ($position = $this->search(array('issements', 'issement'))) != false) {
+        if ( ($position = $this->search(['issements', 'issement'])) != false) {
             if ($this->inR1($position)) {
                 $before = $position - 1;
                 $letter = UTF8::substr($this->word, $before, 1);
@@ -164,7 +164,7 @@ private function step1()
         //      if preceded by eus, delete if in R2, else replace by eux if in R1, otherwise,
         //      if preceded by abl or iqU, delete if in R2, otherwise,
         //      if preceded by ièr or Ièr, replace by i if in RV
-        if ( ($position = $this->search(array('ements', 'ement'))) !== false) {
+        if ( ($position = $this->search(['ements', 'ement'])) !== false) {
 
             // delete if in RV
             if ($this->inRv($position)) {
@@ -172,14 +172,14 @@ private function step1()
             }
 
             // if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
-            if ( ($position = $this->searchIfInR2(array('iv'))) !== false) {
+            if ( ($position = $this->searchIfInR2(['iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position);
-                if ( ($position2 = $this->searchIfInR2(array('at'))) !== false) {
+                if ( ($position2 = $this->searchIfInR2(['at'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position2);
                 }
 
             // if preceded by eus, delete if in R2, else replace by eux if in R1, otherwise,
-            } elseif ( ($position = $this->search(array('eus'))) !== false) {
+            } elseif ( ($position = $this->search(['eus'])) !== false) {
                 if ($this->inR2($position)) {
                     $this->word = UTF8::substr($this->word, 0, $position);
 
@@ -188,11 +188,11 @@ private function step1()
                 }
 
             // if preceded by abl or iqU, delete if in R2, otherwise,
-            } elseif ( ($position = $this->searchIfInR2(array('abl', 'iqU'))) !== false) {
+            } elseif ( ($position = $this->searchIfInR2(['abl', 'iqU'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
             // if preceded by ièr or Ièr, replace by i if in RV
-            } elseif ( ($position = $this->searchIfInRv(array('ièr', 'Ièr'))) !== false) {
+            } elseif ( ($position = $this->searchIfInRv(['ièr', 'Ièr'])) !== false) {
                 $this->word = preg_replace('#(ièr|Ièr)$#u', 'i', $this->word);
             }
             return 3;
@@ -203,7 +203,7 @@ private function step1()
         //      if preceded by abil, delete if in R2, else replace by abl, otherwise,
         //      if preceded by ic, delete if in R2, else replace by iqU, otherwise,
         //      if preceded by iv, delete if in R2
-        if ( ($position = $this->search(array('ités', 'ité'))) !== false) {
+        if ( ($position = $this->search(['ités', 'ité'])) !== false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -211,7 +211,7 @@ private function step1()
             }
 
             // if preceded by abil, delete if in R2, else replace by abl, otherwise,
-            if ( ($position = $this->search(array('abil'))) !== false) {
+            if ( ($position = $this->search(['abil'])) !== false) {
                 if ($this->inR2($position)) {
                     $this->word = UTF8::substr($this->word, 0, $position);
                 } else {
@@ -219,7 +219,7 @@ private function step1()
                 }
 
             // if preceded by ic, delete if in R2, else replace by iqU, otherwise,
-            } elseif ( ($position = $this->search(array('ic'))) !== false) {
+            } elseif ( ($position = $this->search(['ic'])) !== false) {
                 if ($this->inR2($position)) {
                     $this->word = UTF8::substr($this->word, 0, $position);
                 } else {
@@ -227,7 +227,7 @@ private function step1()
                 }
 
             // if preceded by iv, delete if in R2
-            } elseif ( ($position = $this->searchIfInR2(array('iv'))) !== false) {
+            } elseif ( ($position = $this->searchIfInR2(['iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
@@ -237,16 +237,16 @@ private function step1()
         // if   ive   ifs   ives
         //      delete if in R2
         //      if preceded by at, delete if in R2 (and if further preceded by ic, delete if in R2, else replace by iqU)
-        if ( ($position = $this->search(array('ifs', 'ives', 'if', 'ive'))) !== false) {
+        if ( ($position = $this->search(['ifs', 'ives', 'if', 'ive'])) !== false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position = $this->searchIfInR2(array('at'))) !== false) {
+            if ( ($position = $this->searchIfInR2(['at'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
-                if ( ($position2 = $this->search(array('ic'))) !== false) {
+                if ( ($position2 = $this->search(['ic'])) !== false) {
                     if ($this->inR2($position2)) {
                         $this->word = UTF8::substr($this->word, 0, $position2);
                     } else {
@@ -260,14 +260,14 @@ private function step1()
 
         // eaux
         //      replace with eau
-        if ( ($position = $this->search(array('eaux'))) !== false) {
+        if ( ($position = $this->search(['eaux'])) !== false) {
             $this->word = preg_replace('#(eaux)$#u', 'eau', $this->word);
             return 3;
         }
 
         // aux
         //      replace with al if in R1
-        if ( ($position = $this->search(array('aux'))) !== false) {
+        if ( ($position = $this->search(['aux'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(aux)$#u', 'al', $this->word);
             }
@@ -276,7 +276,7 @@ private function step1()
 
         // euse   euses
         //      delete if in R2, else replace by eux if in R1
-        if ( ($position = $this->search(array('euses', 'euse'))) !== false) {
+        if ( ($position = $this->search(['euses', 'euse'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
@@ -289,7 +289,7 @@ private function step1()
 
         // amment
         //      replace with ant if in RV
-        if ( ($position = $this->search(array('amment'))) !== false) {
+        if ( ($position = $this->search(['amment'])) !== false) {
             if ($this->inRv($position)) {
                 $this->word = preg_replace('#(amment)$#u', 'ant', $this->word);
             }
@@ -298,7 +298,7 @@ private function step1()
 
         // emment
         //      replace with ent if in RV
-        if ( ($position = $this->search(array('emment'))) !== false) {
+        if ( ($position = $this->search(['emment'])) !== false) {
             if ($this->inRv($position)) {
                 $this->word = preg_replace('#(emment)$#u', 'ent', $this->word);
             }
@@ -307,7 +307,7 @@ private function step1()
 
         // ment   ments
         //      delete if preceded by a vowel in RV
-        if ( ($position = $this->search(array('ments', 'ment'))) != false) {
+        if ( ($position = $this->search(['ments', 'ment'])) != false) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
             if ( $this->inRv($before) && (in_array($letter, self::$vowels)) ) {
@@ -329,12 +329,12 @@ private function step1()
      *      issent   isses   issez   issiez   issions   issons   it
      *  (Note that the non-vowel itself must also be in RV.)
      */
-    private function step2a()
+    private function step2a(): bool
     {
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'îmes', 'îtes', 'ît', 'ies', 'ie', 'iraIent', 'irais', 'irait', 'irai', 'iras', 'ira', 'irent', 'irez', 'iriez',
             'irions', 'irons', 'iront', 'ir', 'issaIent', 'issais', 'issait', 'issant', 'issantes', 'issante', 'issants',
-            'issent', 'isses', 'issez', 'isse', 'issiez', 'issions', 'issons', 'is', 'it', 'i'))) !== false) {
+            'issent', 'isses', 'issez', 'isse', 'issiez', 'issions', 'issons', 'is', 'it', 'i'])) !== false) {
 
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
@@ -352,13 +352,13 @@ private function step2a()
      * Do step 2b if step 2a was done, but failed to remove a suffix.
      * Step 2b: Other verb suffixes
      */
-    private function step2b()
+    private function step2b(): bool
     {
         // é   ée   ées   és   èrent   er   era   erai   eraIent   erais   erait   eras   erez   eriez   erions   erons   eront   ez   iez
         //      delete
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'ées', 'èrent', 'erais', 'erait', 'erai', 'eraIent', 'eras', 'erez', 'eriez',
-            'erions', 'erons', 'eront', 'era', 'er', 'iez', 'ez','és', 'ée', 'é'))) !== false) {
+            'erions', 'erons', 'eront', 'era', 'er', 'iez', 'ez','és', 'ée', 'é'])) !== false) {
 
             $this->word = UTF8::substr($this->word, 0, $position);
 
@@ -368,9 +368,9 @@ private function step2b()
         // âmes   ât   âtes   a   ai   aIent   ais   ait   ant   ante   antes   ants   as   asse   assent   asses   assiez   assions
         //      delete
         //      if preceded by e, delete
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'âmes', 'âtes', 'ât', 'aIent', 'ais', 'ait', 'antes', 'ante', 'ants', 'ant',
-            'assent', 'asses', 'assiez', 'assions', 'asse', 'as', 'ai', 'a'))) !== false) {
+            'assent', 'asses', 'assiez', 'assions', 'asse', 'as', 'ai', 'a'])) !== false) {
 
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
@@ -386,7 +386,7 @@ private function step2b()
 
         // ions
         //      delete if in R2
-        if ( ($position = $this->searchIfInRv(array('ions'))) !== false) {
+        if ( ($position = $this->searchIfInRv(['ions'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -400,7 +400,7 @@ private function step2b()
     /**
      * Step 3: Replace final Y with i or final ç with c
      */
-    private function step3()
+    private function step3(): void
     {
         $this->word = preg_replace('#(Y)$#u', 'i', $this->word);
         $this->word = preg_replace('#(ç)$#u', 'c', $this->word);
@@ -409,7 +409,7 @@ private function step3()
     /**
      * Step 4: Residual suffix
      */
-    private function step4()
+    private function step4(): bool
     {
         //If the word ends s, not preceded by a, i, o, u, è or s, delete it.
         if (preg_match('#[^aiouès]s$#', $this->word)) {
@@ -419,7 +419,7 @@ private function step4()
         // In the rest of step 4, all tests are confined to the RV region.
         // ion
         //      delete if in R2 and preceded by s or t
-        if ( (($position = $this->searchIfInRv(array('ion'))) !== false) && ($this->inR2($position)) ) {
+        if ( (($position = $this->searchIfInRv(['ion'])) !== false) && ($this->inR2($position)) ) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
             if ( $this->inRv($before) && (($letter == 's') || ($letter == 't')) ) {
@@ -430,25 +430,23 @@ private function step4()
 
         // ier   ière   Ier   Ière
         //      replace with i
-        if ( ($this->searchIfInRv(array('ier', 'ière', 'Ier', 'Ière'))) !== false) {
+        if ( ($this->searchIfInRv(['ier', 'ière', 'Ier', 'Ière'])) !== false) {
             $this->word = preg_replace('#(ier|ière|Ier|Ière)$#u', 'i', $this->word);
             return true;
         }
 
         // e
         //      delete
-        if ( ($this->searchIfInRv(array('e'))) !== false) {
+        if ( ($this->searchIfInRv(['e'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
             return true;
         }
 
         // ë
         //      if preceded by gu, delete
-        if ( ($position = $this->searchIfInRv(array('guë'))) !== false) {
-            if ($this->inRv($position+2)) {
-                $this->word = UTF8::substr($this->word, 0, -1);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(['guë']) !== false && $this->inRv($position+2)) {
+            $this->word = UTF8::substr($this->word, 0, -1);
+            return true;
         }
 
         return false;
@@ -458,9 +456,9 @@ private function step4()
      * Step 5: Undouble
      * If the word ends enn, onn, ett, ell or eill, delete the last letter
      */
-    private function step5()
+    private function step5(): void
     {
-        if ($this->search(array('enn', 'onn', 'ett', 'ell', 'eill')) !== false) {
+        if ($this->search(['enn', 'onn', 'ett', 'ell', 'eill']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
     }
@@ -469,7 +467,7 @@ private function step5()
      * Step 6: Un-accent
      * If the words ends é or è followed by at least one non-vowel, remove the accent from the e.
      */
-    private function step6()
+    private function step6(): void
     {
         $this->word = preg_replace('#(é|è)([^'.$this->plainVowels.']+)$#u', 'e$2', $this->word);
     }
@@ -478,9 +476,9 @@ private function step6()
      * And finally:
      * Turn any remaining I, U and Y letters in the word back into lower case.
      */
-    private function finish()
+    private function finish(): void
     {
-        $this->word = str_replace(array('I','U','Y'), array('i', 'u', 'y'), $this->word);
+        $this->word = str_replace(['I','U','Y'], ['i', 'u', 'y'], $this->word);
     }
 
     /**
@@ -489,7 +487,7 @@ private function finish()
      *  or the end of the word if these positions cannot be found.
      *  (Exceptionally, par, col or tap, at the begining of a word is also taken to define RV as the region to their right.)
      */
-    protected function rv()
+    protected function rv(): bool
     {
         $length = UTF8::strlen($this->word);
 
@@ -512,7 +510,7 @@ protected function rv()
 
         // (Exceptionally, par, col or tap, at the begining of a word is also taken to define RV as the region to their right.)
         $begin3 = UTF8::substr($this->word, 0, 3);
-        if (in_array($begin3, array('par', 'col', 'tap'))) {
+        if (in_array($begin3, ['par', 'col', 'tap'])) {
             $this->rv = UTF8::substr($this->word, 3);
             $this->rvIndex = 3;
             return true;
diff --git a/src/Stemmer/German.php b/src/Stemmer/German.php
index 2410ee7..37ce3d8 100644
--- a/src/Stemmer/German.php
+++ b/src/Stemmer/German.php
@@ -15,11 +15,11 @@ class German extends Stem
     /**
      * All German vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'ä', 'ö', 'ü');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'ä', 'ö', 'ü'];
 
-    protected static $sEndings = array('b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 'r' ,'t');
+    protected static $sEndings = ['b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 'r' ,'t'];
 
-    protected static $stEndings = array('b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 't');
+    protected static $stEndings = ['b', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 't'];
 
     /**
      * {@inheritdoc}
@@ -63,10 +63,10 @@ public function stem($word)
     /**
      * Step 1
      */
-    private function step1()
+    private function step1(): bool
     {
         // delete if in R1
-        if ( ($position = $this->search(array('em', 'ern', 'er'))) !== false) {
+        if ( ($position = $this->search(['em', 'ern', 'er'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -74,12 +74,12 @@ private function step1()
         }
 
         // delete if in R1
-        if ( ($position = $this->search(array('es', 'en', 'e'))) !== false) {
+        if ( ($position = $this->search(['es', 'en', 'e'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
                 //If an ending of group (b) is deleted, and the ending is preceded by niss, delete the final s
-                if ($this->search(array('niss')) !== false) {
+                if ($this->search(['niss']) !== false) {
                     $this->word = UTF8::substr($this->word, 0, -1);
                 }
             }
@@ -87,7 +87,7 @@ private function step1()
         }
 
         // s (preceded by a valid s-ending)
-        if ( ($position = $this->search(array('s'))) !== false) {
+        if ( ($position = $this->search(['s'])) !== false) {
             if ($this->inR1($position)) {
                 $before = $position - 1;
                 $letter = UTF8::substr($this->word, $before, 1);
@@ -105,11 +105,11 @@ private function step1()
     /**
      * Step 2
      */
-    private function step2()
+    private function step2(): bool
     {
         // en   er   est
         //      delete if in R1
-        if ( ($position = $this->search(array('en', 'er', 'est'))) !== false) {
+        if ( ($position = $this->search(['en', 'er', 'est'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -118,7 +118,7 @@ private function step2()
 
         // st (preceded by a valid st-ending, itself preceded by at least 3 letters)
         //      delete if in R1
-        if ( ($position = $this->search(array('st'))) !== false) {
+        if ( ($position = $this->search(['st'])) !== false) {
             if ($this->inR1($position)) {
                 $before = $position - 1;
                 if ($before >= 3) {
@@ -137,17 +137,17 @@ private function step2()
     /**
      * Step 3: d-suffixes
      */
-    private function step3()
+    private function step3(): bool
     {
         // end   ung
         //      delete if in R2
         //      if preceded by ig, delete if in R2 and not preceded by e
-        if ( ($position = $this->search(array('end', 'ung'))) !== false) {
+        if ( ($position = $this->search(['end', 'ung'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->search(array('ig'))) !== false) {
+            if ( ($position2 = $this->search(['ig'])) !== false) {
                 $before = $position2 - 1;
                 $letter = UTF8::substr($this->word, $before, 1);
 
@@ -160,7 +160,7 @@ private function step3()
 
         // ig   ik   isch
         //      delete if in R2 and not preceded by e
-        if ( ($position = $this->search(array('ig', 'ik', 'isch'))) !== false) {
+        if ( ($position = $this->search(['ig', 'ik', 'isch'])) !== false) {
             $before = $position - 1;
             $letter = UTF8::substr($this->word, $before, 1);
 
@@ -173,15 +173,13 @@ private function step3()
         // lich   heit
         //      delete if in R2
         //      if preceded by er or en, delete if in R1
-        if ( ($position = $this->search(array('lich', 'heit'))) != false) {
+        if ( ($position = $this->search(['lich', 'heit'])) != false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->search(array('er', 'en'))) !== false) {
-                if ($this->inR1($position2)) {
-                    $this->word = UTF8::substr($this->word, 0, $position2);
-                }
+            if ( $position2 = $this->search(['er', 'en']) !== false && $this->inR1($position2)) {
+                $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
         }
@@ -189,15 +187,13 @@ private function step3()
         // keit
         //      delete if in R2
         //      if preceded by lich or ig, delete if in R2
-        if ( ($position = $this->search(array('keit'))) != false) {
+        if ( ($position = $this->search(['keit'])) != false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->search(array('lich', 'ig'))) !== false) {
-                if ($this->inR2($position2)) {
-                    $this->word = UTF8::substr($this->word, 0, $position2);
-                }
+            if ( $position2 = $this->search(['lich', 'ig']) !== false && $this->inR2($position2)) {
+                $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
         }
@@ -208,9 +204,9 @@ private function step3()
     /**
      * Finally
      */
-    private function finish()
+    private function finish(): void
     {
         // turn U and Y back into lower case, and remove the umlaut accent from a, o and u.
-        $this->word = str_replace(array('U', 'Y', 'ä', 'ü', 'ö'), array('u', 'y', 'a', 'u', 'o'), $this->word);
+        $this->word = str_replace(['U', 'Y', 'ä', 'ü', 'ö'], ['u', 'y', 'a', 'u', 'o'], $this->word);
     }
 }
diff --git a/src/Stemmer/Italian.php b/src/Stemmer/Italian.php
index 40c9d86..3956f97 100644
--- a/src/Stemmer/Italian.php
+++ b/src/Stemmer/Italian.php
@@ -15,7 +15,7 @@ class Italian extends Stem
     /**
      * All Italian vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'à', 'è', 'ì', 'ò', 'ù');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'à', 'è', 'ì', 'ò', 'ù'];
 
     /**
      * {@inheritdoc}
@@ -32,7 +32,7 @@ public function stem($word)
         $this->word = UTF8::strtolower($word);
 
         // First, replace all acute accents by grave accents.
-        $this->word = str_replace(array('á', 'é', 'í', 'ó', 'ú'), array('à', 'è', 'ì', 'ò', 'ù'), $this->word);
+        $this->word = str_replace(['á', 'é', 'í', 'ó', 'ú'], ['à', 'è', 'ì', 'ò', 'ù'], $this->word);
 
         //And, as in French, put u after q, and u, i between vowels into upper case. (See note on vowel marking.) The vowels are then
         $this->word = preg_replace('#([q])u#u', '$1U', $this->word);
@@ -63,21 +63,21 @@ public function stem($word)
     /**
      * Step 0: Attached pronoun
      */
-    private function step0()
+    private function step0(): bool
     {
         // Search for the longest among the following suffixes
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'gliela', 'gliele', 'glieli', 'glielo', 'gliene',
             'sene', 'mela', 'mele', 'meli', 'melo', 'mene', 'tela', 'tele', 'teli', 'telo', 'tene', 'cela',
             'cele', 'celi', 'celo', 'cene', 'vela', 'vele', 'veli', 'velo', 'vene',
-            'gli', 'la', 'le', 'li', 'lo', 'mi', 'ne', 'si', 'ti', 'vi', 'ci'))) !== false) {
+            'gli', 'la', 'le', 'li', 'lo', 'mi', 'ne', 'si', 'ti', 'vi', 'ci'])) !== false) {
 
             $suffixe = UTF8::substr($this->word, $position);
 
             // following one of (in RV)
              // a
-            $a = array('ando', 'endo');
-            $a = array_map(function($item) use ($suffixe) {
+            $a = ['ando', 'endo'];
+            $a = array_map(function(string $item) use ($suffixe): string {
                 return $item . $suffixe;
             }, $a);
             // In case of (a) the suffix is deleted
@@ -86,8 +86,8 @@ private function step0()
             }
 
             //b
-            $b = array('ar', 'er', 'ir');
-            $b = array_map(function($item) use ($suffixe) {
+            $b = ['ar', 'er', 'ir'];
+            $b = array_map(function(string $item) use ($suffixe): string {
                 return $item . $suffixe;
             }, $b);
             // in case (b) it is replace by e
@@ -104,37 +104,37 @@ private function step0()
     /**
      * Step 1: Standard suffix removal
      */
-    private function step1()
+    private function step1(): bool
     {
         // amente
         //      delete if in R1
         //      if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
         //      if preceded by os, ic or abil, delete if in R2
-        if ( ($position = $this->search(array('amente'))) !== false) {
+        if ( ($position = $this->search(['amente'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
             // if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
-            if ( ($position2 = $this->searchIfInR2(array('iv'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
-                if ( ($position3 = $this->searchIfInR2(array('at'))) !== false) {
+                if ( ($position3 = $this->searchIfInR2(['at'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position3);
                 }
 
                 // if preceded by os, ic or ad, delete if in R2
-            } elseif ( ($position4 = $this->searchIfInR2(array('os', 'ic', 'abil'))) != false) {
+            } elseif ( ($position4 = $this->searchIfInR2(['os', 'ic', 'abil'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position4);
             }
             return true;
         }
 
         // delete if in R2
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'ibili', 'atrice', 'abili', 'abile', 'ibile', 'atrici', 'mente',
             'anza', 'anze', 'iche', 'ichi', 'ismo', 'ismi', 'ista', 'iste', 'isti', 'istà', 'istè', 'istì', 'ante', 'anti',
             'ico', 'ici', 'ica', 'ice', 'oso', 'osi', 'osa', 'ose'
-        ))) !== false) {
+        ])) !== false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
@@ -145,14 +145,12 @@ private function step1()
         // azione   azioni   atore   atori
         //      delete if in R2
         //      if preceded by ic, delete if in R2
-        if ( ($position = $this->search(array('azione', 'azioni', 'atore', 'atori'))) !== false) {
+        if ( ($position = $this->search(['azione', 'azioni', 'atore', 'atori'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
 
-                if ( ($position2 = $this->search(array('ic'))) !== false) {
-                    if ($this->inR2($position2)) {
-                        $this->word = UTF8::substr($this->word, 0, $position2);
-                    }
+                if ( $position2 = $this->search(['ic']) !== false && $this->inR2($position2)) {
+                    $this->word = UTF8::substr($this->word, 0, $position2);
                 }
             }
             return true;
@@ -160,7 +158,7 @@ private function step1()
 
         // logia   logie
         //      replace with log if in R2
-        if ( ($position = $this->search(array('logia', 'logie'))) !== false) {
+        if ( ($position = $this->search(['logia', 'logie'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(logia|logie)$#u', 'log', $this->word);
             }
@@ -169,7 +167,7 @@ private function step1()
 
         // uzione   uzioni   usione   usioni
         //      replace with u if in R2
-        if ( ($position = $this->search(array('uzione', 'uzioni', 'usione', 'usioni'))) !== false) {
+        if ( ($position = $this->search(['uzione', 'uzioni', 'usione', 'usioni'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(uzione|uzioni|usione|usioni)$#u', 'u', $this->word);
             }
@@ -178,7 +176,7 @@ private function step1()
 
         // enza   enze
         //      replace with ente if in R2
-        if ( ($position = $this->search(array('enza', 'enze'))) !== false) {
+        if ( ($position = $this->search(['enza', 'enze'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(enza|enze)$#u', 'ente', $this->word);
             }
@@ -187,7 +185,7 @@ private function step1()
 
         // amento   amenti   imento   imenti
         //      delete if in RV
-        if ( ($position = $this->search(array('amento', 'amenti', 'imento', 'imenti'))) !== false) {
+        if ( ($position = $this->search(['amento', 'amenti', 'imento', 'imenti'])) !== false) {
             if ($this->inRv($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -197,12 +195,12 @@ private function step1()
         // ità
         //      delete if in R2
         //      if preceded by abil, ic or iv, delete if in R2
-        if ( ($position = $this->search(array('ità'))) !== false) {
+        if ( ($position = $this->search(['ità'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->searchIfInR2(array('abil', 'ic', 'iv'))) != false) {
+            if ( ($position2 = $this->searchIfInR2(['abil', 'ic', 'iv'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -211,14 +209,14 @@ private function step1()
         // ivo   ivi   iva   ive
         //      delete if in R2
         //      if preceded by at, delete if in R2 (and if further preceded by ic, delete if in R2)
-        if ( ($position = $this->search(array('ivo', 'ivi', 'iva', 'ive'))) !== false) {
+        if ( ($position = $this->search(['ivo', 'ivi', 'iva', 'ive'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->searchIfInR2(array('at'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['at'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
-                if ( ($position3 = $this->searchIfInR2(array('ic'))) !== false) {
+                if ( ($position3 = $this->searchIfInR2(['ic'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position3);
                 }
             }
@@ -232,16 +230,16 @@ private function step1()
      * Step 2: Verb suffixes
      * Search for the longest among the following suffixes in RV, and if found, delete.
      */
-    private function step2()
+    private function step2(): void
     {
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'assimo', 'assero', 'eranno', 'erebbero', 'erebbe', 'eremmo', 'ereste', 'eresti', 'essero', 'iranno', 'irebbero', 'irebbe', 'iremmo',
             'iscano', 'ireste', 'iresti', 'iscono', 'issero',
             'avamo', 'arono', 'avano', 'avate', 'eremo', 'erete', 'erono', 'evamo', 'evano', 'evate', 'ivamo', 'ivano', 'ivate', 'iremo', 'irete', 'irono',
             'ammo', 'ando', 'asse', 'assi', 'emmo', 'enda', 'ende', 'endi', 'endo', 'erai', 'erei', 'Yamo', 'iamo', 'immo', 'irà', 'irai', 'irei',
             'isca', 'isce', 'isci', 'isco',
             'ano', 'are', 'ata', 'ate', 'ati', 'ato', 'ava', 'avi', 'avo', 'erà', 'ere', 'erò', 'ete', 'eva',
-            'evi', 'evo', 'ire', 'ita', 'ite', 'iti', 'ito', 'iva', 'ivi', 'ivo', 'ono', 'uta', 'ute', 'uti', 'uto', 'irò', 'ar', 'ir'))) !== false) {
+            'evi', 'evo', 'ire', 'ita', 'ite', 'iti', 'ito', 'iva', 'ivi', 'ivo', 'ono', 'uta', 'ute', 'uti', 'uto', 'irò', 'ar', 'ir'])) !== false) {
 
             $this->word = UTF8::substr($this->word, 0, $position);
         }
@@ -251,12 +249,12 @@ private function step2()
      * Step 3a
      * Delete a final a, e, i, o, à, è, ì or ò if it is in RV, and a preceding i if it is in RV
      */
-    private function step3a()
+    private function step3a(): bool
     {
-        if ($this->searchIfInRv(array('a', 'e', 'i', 'o', 'à', 'è', 'ì', 'ò')) !== false) {
+        if ($this->searchIfInRv(['a', 'e', 'i', 'o', 'à', 'è', 'ì', 'ò']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
 
-            if ($this->searchIfInRv(array('i')) !== false) {
+            if ($this->searchIfInRv(['i']) !== false) {
                 $this->word = UTF8::substr($this->word, 0, -1);
             }
             return true;
@@ -268,12 +266,12 @@ private function step3a()
      * Step 3b
      * Replace final ch (or gh) with c (or g) if in RV (crocch -> crocc)
      */
-    private function step3b()
+    private function step3b(): void
     {
-        if ($this->searchIfInRv(array('ch')) !== false) {
+        if ($this->searchIfInRv(['ch']) !== false) {
             $this->word = preg_replace('#(ch)$#u', 'c', $this->word);
 
-        } elseif ($this->searchIfInRv(array('gh')) !== false) {
+        } elseif ($this->searchIfInRv(['gh']) !== false) {
             $this->word = preg_replace('#(gh)$#u', 'g', $this->word);
         }
     }
@@ -282,8 +280,8 @@ private function step3b()
      * Finally
      * turn I and U back into lower case
      */
-    private function finish()
+    private function finish(): void
     {
-        $this->word = str_replace(array('I', 'U'), array('i', 'u'), $this->word);
+        $this->word = str_replace(['I', 'U'], ['i', 'u'], $this->word);
     }
 }
diff --git a/src/Stemmer/Norwegian.php b/src/Stemmer/Norwegian.php
index b44b722..19f1da8 100644
--- a/src/Stemmer/Norwegian.php
+++ b/src/Stemmer/Norwegian.php
@@ -15,12 +15,12 @@ class Norwegian extends Stem
     /**
      * All norwegian vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'æ', 'å', 'ø');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'æ', 'å', 'ø'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -52,12 +52,11 @@ public function stem($word)
      * or k not preceded by a vowel
      *
      * @param string $ending
-     * @return boolean
      */
-    private function hasValidSEnding($word)
+    private function hasValidSEnding(string $word): bool
     {
         $lastLetter = UTF8::substr($word, -1, 1);
-        if (in_array($lastLetter, array('b', 'c', 'd', 'f', 'g', 'h', 'j', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y', 'z'))) {
+        if (in_array($lastLetter, ['b', 'c', 'd', 'f', 'g', 'h', 'j', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y', 'z'])) {
             return true;
         }
         if ($lastLetter == 'k') {
@@ -73,43 +72,44 @@ private function hasValidSEnding($word)
      * Step 1
      * Search for the longest among the following suffixes in R1, and perform the action indicated.
      */
-    private function step1()
+    private function step1(): ?bool
     {
         //  erte   ert
         //      replace with er
-        if ( ($position = $this->searchIfInR1(array('erte', 'ert'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['erte', 'ert'])) !== false) {
             $this->word = preg_replace('#(erte|ert)$#u', 'er', $this->word);
             return true;
         }
 
          // a   e   ede   ande   ende   ane   ene   hetene   en   heten   ar   er   heter   as   es   edes   endes   enes   hetenes   ens   hetens   ers   ets   et   het   ast
         //      delete
-        if ( ($position = $this->searchIfInR1(array(
+        if ( ($position = $this->searchIfInR1([
             'hetenes', 'hetene', 'hetens', 'heten', 'endes', 'heter', 'ande', 'ende', 'enes', 'edes', 'ede', 'ane',
             'ene', 'het', 'ers', 'ets', 'ast', 'ens', 'en', 'ar', 'er', 'as', 'es', 'et', 'a', 'e'
-        ))) !== false) {
+        ])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         //  s
         //      delete if preceded by a valid s-ending
-        if ( ($position = $this->searchIfInR1(array('s'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['s'])) !== false) {
             $word = UTF8::substr($this->word, 0, $position);
             if ($this->hasValidSEnding($word)) {
                 $this->word = $word;
             }
             return true;
         }
+        return null;
     }
 
     /**
      * Step 2
      * If the word ends dt or vt in R1, delete the t.
      */
-    private function step2()
+    private function step2(): void
     {
-        if ($this->searchIfInR1(array('dt', 'vt')) !== false) {
+        if ($this->searchIfInR1(['dt', 'vt']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
     }
@@ -118,12 +118,12 @@ private function step2()
      * Step 3:
      * Search for the longest among the following suffixes in R1, and if found, delete.
      */
-    private function step3()
+    private function step3(): void
     {
         // leg   eleg   ig   eig   lig   elig   els   lov   elov   slov   hetslov
-        if ( ($position = $this->searchIfInR1(array(
+        if ( ($position = $this->searchIfInR1([
             'hetslov', 'eleg', 'elov', 'slov', 'elig', 'eig', 'lig', 'els', 'lov', 'leg', 'ig'
-        ))) !== false) {
+        ])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
         }
     }
diff --git a/src/Stemmer/Portuguese.php b/src/Stemmer/Portuguese.php
index 485aba0..b335d93 100644
--- a/src/Stemmer/Portuguese.php
+++ b/src/Stemmer/Portuguese.php
@@ -15,7 +15,7 @@ class Portuguese extends Stem
     /**
      * All Portuguese vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'á', 'é', 'í', 'ó', 'ú', 'â', 'ê', 'ô');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'á', 'é', 'í', 'ó', 'ú', 'â', 'ê', 'ô'];
 
     /**
      * {@inheritdoc}
@@ -29,7 +29,7 @@ public function stem($word)
 
         $this->word = UTF8::strtolower($word);
 
-        $this->word = str_replace(array('ã', 'õ'), array('a~', 'o~'), $this->word);
+        $this->word = str_replace(['ã', 'õ'], ['a~', 'o~'], $this->word);
 
         $this->rv();
         $this->r1();
@@ -57,13 +57,13 @@ public function stem($word)
     /**
      * Step 1: Standard suffix removal
      */
-    private function step1()
+    private function step1(): bool
     {
         // delete if in R2
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'amentos', 'imentos', 'adoras', 'adores', 'amento', 'imento', 'adora', 'istas', 'ismos', 'antes', 'ância',
             'ezas', 'eza', 'icos', 'icas', 'ismo', 'ável', 'ível', 'ista', 'oso',
-            'osos', 'osas', 'osa', 'ico', 'ica', 'ador', 'aça~o', 'aço~es' , 'ante'))) !== false) {
+            'osos', 'osas', 'osa', 'ico', 'ica', 'ador', 'aça~o', 'aço~es' , 'ante'])) !== false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
@@ -73,7 +73,7 @@ private function step1()
 
         // logía   logías
         //      replace with log if in R2
-        if ( ($position = $this->search(array('logías', 'logía'))) !== false) {
+        if ( ($position = $this->search(['logías', 'logía'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(logías|logía)$#u', 'log', $this->word);
             }
@@ -82,7 +82,7 @@ private function step1()
 
         // ución   uciones
         //      replace with u if in R2
-        if ( ($position = $this->search(array('uciones', 'ución'))) !== false) {
+        if ( ($position = $this->search(['uciones', 'ución'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(uciones|ución)$#u', 'u', $this->word);
             }
@@ -91,7 +91,7 @@ private function step1()
 
         // ência    ências
         //      replace with ente if in R2
-        if ( ($position = $this->search(array('ências', 'ência'))) !== false) {
+        if ( ($position = $this->search(['ências', 'ência'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(ências|ência)$#u', 'ente', $this->word);
             }
@@ -102,7 +102,7 @@ private function step1()
         //      delete if in R1
         //      if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
         //      if preceded by os, ic or ad, delete if in R2
-        if ( ($position = $this->search(array('amente'))) !== false) {
+        if ( ($position = $this->search(['amente'])) !== false) {
 
             // delete if in R1
             if ($this->inR1($position)) {
@@ -110,14 +110,14 @@ private function step1()
             }
 
             // if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
-            if ( ($position2 = $this->searchIfInR2(array('iv'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
-                if ( ($position3 = $this->searchIfInR2(array('at'))) !== false) {
+                if ( ($position3 = $this->searchIfInR2(['at'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position3);
                 }
 
                 // if preceded by os, ic or ad, delete if in R2
-            } elseif ( ($position4 = $this->searchIfInR2(array('os', 'ic', 'ad'))) !== false) {
+            } elseif ( ($position4 = $this->searchIfInR2(['os', 'ic', 'ad'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position4);
             }
             return true;
@@ -126,7 +126,7 @@ private function step1()
         // mente
         //      delete if in R2
         //      if preceded by ante, avel or ível, delete if in R2
-        if ( ($position = $this->search(array('mente'))) !== false) {
+        if ( ($position = $this->search(['mente'])) !== false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -134,7 +134,7 @@ private function step1()
             }
 
             // if preceded by ante, avel or ível, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('ante', 'avel', 'ível'))) != false) {
+            if ( ($position2 = $this->searchIfInR2(['ante', 'avel', 'ível'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -143,7 +143,7 @@ private function step1()
         // idade   idades
         //      delete if in R2
         //      if preceded by abil, ic or iv, delete if in R2
-        if ( ($position = $this->search(array('idades', 'idade'))) !== false) {
+        if ( ($position = $this->search(['idades', 'idade'])) !== false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -151,7 +151,7 @@ private function step1()
             }
 
             // if preceded by abil, ic or iv, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('abil', 'ic', 'iv'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['abil', 'ic', 'iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -160,7 +160,7 @@ private function step1()
         // iva   ivo   ivas   ivos
         //      delete if in R2
         //      if preceded by at, delete if in R2
-        if ( ($position = $this->search(array('ivas', 'ivos', 'iva', 'ivo'))) !== false) {
+        if ( ($position = $this->search(['ivas', 'ivos', 'iva', 'ivo'])) !== false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -168,7 +168,7 @@ private function step1()
             }
 
             // if preceded by at, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('at'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['at'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -176,7 +176,7 @@ private function step1()
 
         // ira   iras
         //      replace with ir if in RV and preceded by e
-        if ( ($position = $this->search(array('iras', 'ira'))) !== false) {
+        if ( ($position = $this->search(['iras', 'ira'])) !== false) {
 
             if ($this->inRv($position)) {
                 $before = $position -1;
@@ -196,9 +196,9 @@ private function step1()
      * Step 2: Verb suffixes
      * Search for the longest among the following suffixes in RV, and if found, delete.
      */
-    private function step2()
+    private function step2(): bool
     {
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'aríamos', 'eríamos', 'iríamos', 'ássemos', 'êssemos', 'íssemos',
             'aríeis', 'eríeis', 'iríeis', 'ásseis', 'ésseis', 'ísseis', 'áramos', 'éramos', 'íramos', 'ávamos',
             'aremos', 'eremos', 'iremos',
@@ -211,7 +211,7 @@ private function step2()
             'emos', 'imos', 'iras',
             'ada', 'ida', 'ará', 'ara', 'erá', 'era', 'irá', 'ava', 'iam', 'ado', 'ido', 'ias', 'ais', 'eis', 'ira',
             'ia', 'ei', 'am', 'em', 'ar', 'er', 'ir', 'as', 'es', 'is', 'eu', 'iu', 'ou',
-        ))) !== false) {
+        ])) !== false) {
 
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
@@ -223,10 +223,10 @@ private function step2()
      * Step 3: d-suffixes
      *
      */
-    private function step3()
+    private function step3(): bool
     {
         // Delete suffix i if in RV and preceded by c
-        if ($this->searchIfInRv(array('i')) !== false) {
+        if ($this->searchIfInRv(['i']) !== false) {
             $letter = UTF8::substr($this->word, -2, 1);
 
             if ($letter == 'c') {
@@ -240,10 +240,10 @@ private function step3()
     /**
      * Step 4
      */
-    private function step4()
+    private function step4(): bool
     {
         // If the word ends with one of the suffixes "os   a   i   o   á   í   ó" in RV, delete it
-        if ( ($position = $this->searchIfInRv(array('os', 'a', 'i', 'o','á', 'í', 'ó'))) !== false) {
+        if ( ($position = $this->searchIfInRv(['os', 'a', 'i', 'o','á', 'í', 'ó'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
@@ -253,19 +253,16 @@ private function step4()
     /**
      * Step 5
      */
-    private function step5()
+    private function step5(): bool
     {
         // If the word ends with one of "e   é   ê" in RV, delete it, and if preceded by gu (or ci) with the u (or i) in RV, delete the u (or i).
-        if ($this->searchIfInRv(array('e', 'é', 'ê')) !== false) {
+        if ($this->searchIfInRv(['e', 'é', 'ê']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
-
-            if ( ($position2 = $this->search(array('gu', 'ci'))) !== false) {
-                if ($this->inRv(($position2+1))) {
-                    $this->word = UTF8::substr($this->word, 0, -1);
-                }
+            if ( $position2 = $this->search(['gu', 'ci']) !== false && $this->inRv(($position2+1))) {
+                $this->word = UTF8::substr($this->word, 0, -1);
             }
             return true;
-        } else if ($this->search(array('ç')) !== false) {
+        } elseif ($this->search(['ç']) !== false) {
             $this->word = preg_replace('#(ç)$#u', 'c', $this->word);
             return true;
         }
@@ -275,9 +272,9 @@ private function step5()
     /**
      * Finally
      */
-    private function finish()
+    private function finish(): void
     {
         // turn U and Y back into lower case, and remove the umlaut accent from a, o and u.
-        $this->word = str_replace(array('a~', 'o~'), array('ã', 'õ'), $this->word);
+        $this->word = str_replace(['a~', 'o~'], ['ã', 'õ'], $this->word);
     }
 }
diff --git a/src/Stemmer/Romanian.php b/src/Stemmer/Romanian.php
index 3e9edd1..5c9d757 100644
--- a/src/Stemmer/Romanian.php
+++ b/src/Stemmer/Romanian.php
@@ -15,12 +15,12 @@ class Romanian extends Stem
     /**
      * All Romanian vowels
      */
-    protected static $vowels = array('a', 'ă', 'â', 'e', 'i', 'î', 'o', 'u');
+    protected static $vowels = ['a', 'ă', 'â', 'e', 'i', 'î', 'o', 'u'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): ?string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -65,13 +65,12 @@ public function stem($word)
     /**
      * Step 0: Removal of plurals (and other simplifications)
      * Search for the longest among the following suffixes, and, if it is in R1, perform the action indicated.
-     * @return boolean
      */
-    private function step0()
+    private function step0(): bool
     {
         // ul   ului
         //      delete
-        if ( ($position = $this->search(array('ul', 'ului'))) !== false) {
+        if ( ($position = $this->search(['ul', 'ului'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -80,7 +79,7 @@ private function step0()
 
         // aua
         //      replace with a
-        if ( ($position = $this->search(array('aua'))) !== false) {
+        if ( ($position = $this->search(['aua'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(aua)$#u', 'a', $this->word);
             }
@@ -89,7 +88,7 @@ private function step0()
 
         // ea   ele   elor
         //      replace with e
-        if ( ($position = $this->search(array('ea', 'ele', 'elor'))) !== false) {
+        if ( ($position = $this->search(['ea', 'ele', 'elor'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ea|ele|elor)$#u', 'e', $this->word);
             }
@@ -98,7 +97,7 @@ private function step0()
 
         // ii   iua   iei   iile   iilor   ilor
         //      replace with i
-        if ( ($position = $this->search(array('ii', 'iua', 'iei', 'iile', 'iilor', 'ilor'))) !== false) {
+        if ( ($position = $this->search(['ii', 'iua', 'iei', 'iile', 'iilor', 'ilor'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ii|iua|iei|iile|iilor|ilor)$#u', 'i', $this->word);
             }
@@ -107,7 +106,7 @@ private function step0()
 
         // ile
         //      replace with i if not preceded by ab
-        if ( ($position = $this->search(array('ile'))) !== false) {
+        if ( ($position = $this->search(['ile'])) !== false) {
             if ($this->inR1($position)) {
                 $before = UTF8::substr($this->word, ($position-2), 2);
 
@@ -120,7 +119,7 @@ private function step0()
 
         // atei
         //      replace with at
-        if ( ($position = $this->search(array('atei'))) != false) {
+        if ( ($position = $this->search(['atei'])) != false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(atei)$#u', 'at', $this->word);
             }
@@ -129,7 +128,7 @@ private function step0()
 
         // aţie   aţia
         //      replace with aţi
-        if ( ($position = $this->search(array('aţie', 'aţia'))) !== false) {
+        if ( ($position = $this->search(['aţie', 'aţia'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(aţie|aţia)$#u', 'aţi', $this->word);
             }
@@ -143,13 +142,12 @@ private function step0()
      * Step 1: Reduction of combining suffixes
      * Search for the longest among the following suffixes, and, if it is in R1, preform the replacement action indicated.
      * Then repeat this step until no replacement occurs.
-     * @return boolean
      */
-    private function step1()
+    private function step1(): bool
     {
         // abilitate   abilitati   abilităi   abilităţi
         //      replace with abil
-        if ( ($position = $this->search(array('abilitate', 'abilitati', 'abilităi', 'abilităţi'))) !== false) {
+        if ( ($position = $this->search(['abilitate', 'abilitati', 'abilităi', 'abilităţi'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(abilitate|abilitati|abilităi|abilităţi)$#u', 'abil', $this->word);
             }
@@ -158,7 +156,7 @@ private function step1()
 
         // ibilitate
         //      replace with ibil
-        if ( ($position = $this->search(array('ibilitate'))) !== false) {
+        if ( ($position = $this->search(['ibilitate'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ibilitate)$#u', 'ibil', $this->word);
             }
@@ -167,7 +165,7 @@ private function step1()
 
         // ivitate   ivitati   ivităi   ivităţi
         //      replace with iv
-        if ( ($position = $this->search(array('ivitate', 'ivitati', 'ivităi', 'ivităţi'))) !== false) {
+        if ( ($position = $this->search(['ivitate', 'ivitati', 'ivităi', 'ivităţi'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ivitate|ivitati|ivităi|ivităţi)$#u', 'iv', $this->word);
             }
@@ -176,9 +174,9 @@ private function step1()
 
         // icitate   icitati   icităi   icităţi   icator   icatori   iciv   iciva   icive   icivi   icivă   ical   icala   icale   icali   icală
         //      replace with ic
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'icitate', 'icitati', 'icităi', 'icităţi', 'icatori', 'icator', 'iciva',
-            'icive', 'icivi', 'icivă', 'icala', 'icale', 'icali', 'icală', 'iciv', 'ical'))) !== false) {
+            'icive', 'icivi', 'icivă', 'icala', 'icale', 'icali', 'icală', 'iciv', 'ical'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(icitate|icitati|icităi|icităţi|cator|icatori|iciva|icive|icivi|icivă|icala|icale|icali|icală|ical|iciv)$#u', 'ic', $this->word);
             }
@@ -187,7 +185,7 @@ private function step1()
 
         // ativ   ativa   ative   ativi   ativă   aţiune   atoare   ator   atori   ătoare   ător   ători
         //      replace with at
-        if ( ($position = $this->search(array('ativa', 'ative', 'ativi', 'ativă', 'ativ', 'aţiune', 'atoare', 'atori', 'ătoare', 'ători', 'ător', 'ator'))) !== false) {
+        if ( ($position = $this->search(['ativa', 'ative', 'ativi', 'ativă', 'ativ', 'aţiune', 'atoare', 'atori', 'ătoare', 'ători', 'ător', 'ator'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(ativa|ative|ativi|ativă|ativ|aţiune|atoare|atori|ătoare|ători|ător|ator)$#u', 'at', $this->word);
             }
@@ -196,7 +194,7 @@ private function step1()
 
         // itiv   itiva   itive   itivi   itivă   iţiune   itoare   itor   itori
         //      replace with it
-        if ( ($position = $this->search(array('itiva', 'itive', 'itivi', 'itivă', 'itiv', 'iţiune', 'itoare', 'itori', 'itor'))) !== false) {
+        if ( ($position = $this->search(['itiva', 'itive', 'itivi', 'itivă', 'itiv', 'iţiune', 'itoare', 'itori', 'itor'])) !== false) {
             if ($this->inR1($position)) {
                 $this->word = preg_replace('#(itiva|itive|itivi|itivă|itiv|iţiune|itoare|itori|itor)$#u', 'it', $this->word);
             }
@@ -209,22 +207,21 @@ private function step1()
     /**
      * Step 2: Removal of 'standard' suffixes
      * Search for the longest among the following suffixes, and, if it is in R2, perform the action indicated.
-     * @return boolean
      */
-    private function step2()
+    private function step2(): bool
     {
         // atori   itate   itati, ităţi, abila   abile   abili   abilă, ibila   ibile   ibili   ibilă
         // anta, ante, anti, antă, ator, ibil, oasa   oasă   oase, ităi, abil
         // osi   oşi   ant   ici   ică iva   ive   ivi   ivă ata   ată   ati   ate, ata   ată   ati   ate uta   ută   uti   ute, ita   ită   iti   ite  ica   ice
         // at, os, iv, ut, it, ic
         //      delete
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'atori', 'itate', 'itati', 'ităţi', 'abila', 'abile', 'abili', 'abilă', 'ibila', 'ibile', 'ibili', 'ibilă',
             'anta', 'ante', 'anti', 'antă', 'ator', 'ibil', 'oasa', 'oasă', 'oase', 'ităi', 'abil',
             'osi', 'oşi', 'ant', 'ici', 'ică', 'iva', 'ive', 'ivi', 'ivă', 'ata', 'ată', 'ati', 'ate', 'ata', 'ată',
             'ati', 'ate', 'uta', 'ută', 'uti', 'ute', 'ita', 'ită', 'iti', 'ite', 'ica', 'ice',
             'at', 'os', 'iv', 'ut', 'it', 'ic'
-        ))) !== false) {
+        ])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
@@ -233,7 +230,7 @@ private function step2()
 
         // iune   iuni
         //      delete if preceded by ţ, and replace the ţ by t.
-        if ( ($position = $this->search(array('iune', 'iuni'))) !== false) {
+        if ( ($position = $this->search(['iune', 'iuni'])) !== false) {
             if ($this->inR2($position)) {
                 $before = $position - 1;
                 $letter = UTF8::substr($this->word, $before, 1);
@@ -247,7 +244,7 @@ private function step2()
 
         // ism   isme   ist   ista   iste   isti   istă   işti
         //      replace with ist
-        if ( ($position = $this->search(array('isme', 'ism', 'ista', 'iste', 'isti', 'istă', 'işti', 'ist'))) !== false) {
+        if ( ($position = $this->search(['isme', 'ism', 'ista', 'iste', 'isti', 'istă', 'işti', 'ist'])) !== false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(isme|ism|ista|iste|isti|istă|işti|ist)$#u', 'ist', $this->word);
             }
@@ -262,7 +259,7 @@ private function step2()
      * Do step 3 if no suffix was removed either by step 1 or step 2.
      * @return boolean
      */
-    private function step3()
+    private function step3(): ?bool
     {
         // are   ere   ire   âre   ind   ând   indu   ându   eze   ească   ez   ezi   ează   esc   eşti
         // eşte   ăsc   ăşti   ăşte   am   ai   au   eam   eai   ea   eaţi   eau   iam   iai   ia   iaţi
@@ -270,7 +267,7 @@ private function step3()
         // âşi   ârăm   ârăţi   âră   asem   aseşi   ase   aserăm   aserăţi   aseră   isem   iseşi   ise
         // iserăm   iserăţi   iseră   âsem   âseşi   âse   âserăm   âserăţi   âseră   usem   useşi   use   userăm   userăţi   useră
         //      delete if preceded in RV by a consonant or u
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'userăţi', 'iserăţi', 'âserăţi', 'aserăţi',
             'userăm', 'iserăm', 'âserăm', 'aserăm',
             'iseră', 'âseşi', 'useră', 'âseră', 'useşi', 'iseşi', 'aseră', 'aseşi', 'ârăţi', 'irăţi', 'urăţi', 'arăţi', 'ească',
@@ -278,7 +275,7 @@ private function step3()
             'âse', 'use', 'ise', 'ase', 'âră', 'iră', 'işi', 'ură', 'uşi', 'ară', 'aşi', 'âşi', 'iau', 'iai', 'iam', 'eau', 'eai', 'eam', 'ăsc',
             'are', 'ere', 'ire', 'âre', 'ind', 'ând', 'eze', 'ezi', 'esc',
             'âi', 'ui', 'ia', 'ea', 'au', 'ai', 'am', 'ez'
-        ))) !== false) {
+        ])) !== false) {
             if ($this->inRv($position)) {
                 $before = $position - 1;
                 if ($this->inRv($before)) {
@@ -296,27 +293,26 @@ private function step3()
 
         // ăm   aţi   em   eţi   im   iţi   âm   âţi   seşi   serăm   serăţi   seră   sei   se   sesem   seseşi   sese   seserăm   seserăţi   seseră
         //      delete
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'seserăm', 'seserăţi', 'seseră', 'seseşi', 'sesem', 'serăţi', 'serăm', 'seşi', 'sese', 'seră',
             'aţi', 'eţi', 'iţi', 'âţi', 'sei', 'se', 'ăm', 'âm', 'em', 'im'
-        ))) !== false) {
+        ])) !== false) {
             if ($this->inRv($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
             return true;
         }
+        return null;
     }
 
     /**
      * Step 4: Removal of final vowel
      */
-    private function step4()
+    private function step4(): bool
     {
         // Search for the longest among the suffixes "a   e   i   ie   ă " and, if it is in RV, delete it.
-        if ( ($position = $this->search(array('a', 'ie', 'e', 'i', 'ă'))) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-            }
+        if ( $position = $this->search(['a', 'ie', 'e', 'i', 'ă']) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
         }
 
         return true;
@@ -326,9 +322,9 @@ private function step4()
      * Finally
      * Turn I, U back into i, u
      */
-    private function finish()
+    private function finish(): void
     {
         // Turn I, U back into i, u
-        $this->word = str_replace(array('I', 'U'), array('i', 'u'), $this->word);
+        $this->word = str_replace(['I', 'U'], ['i', 'u'], $this->word);
     }
 }
diff --git a/src/Stemmer/Russian.php b/src/Stemmer/Russian.php
index cd18dbf..6d12cac 100644
--- a/src/Stemmer/Russian.php
+++ b/src/Stemmer/Russian.php
@@ -15,46 +15,46 @@ class Russian extends Stem
     /**
      * All russian vowels
      */
-    protected static $vowels = array('а', 'е', 'и', 'о', 'у', 'ы', 'э', 'ю', 'я');
+    protected static $vowels = ['а', 'е', 'и', 'о', 'у', 'ы', 'э', 'ю', 'я'];
 
-    protected static $perfectiveGerund = array(
-        array('вшись', 'вши', 'в'),
-        array('ывшись', 'ившись', 'ывши', 'ивши', 'ив', 'ыв')
-    );
+    protected static $perfectiveGerund = [
+        ['вшись', 'вши', 'в'],
+        ['ывшись', 'ившись', 'ывши', 'ивши', 'ив', 'ыв']
+    ];
 
-    protected static $adjective = array(
+    protected static $adjective = [
         'ыми', 'ими', 'ему', 'ому', 'его', 'ого', 'ее', 'ие', 'ые', 'ое', 'ей', 'ий',
         'ый', 'ой', 'ем', 'им', 'ым','ом','их', 'ых', 'ую', 'юю', 'ая', 'яя', 'ою', 'ею'
-    );
+    ];
 
-    protected static $participle = array(
-        array('ем', 'нн', 'вш', 'ющ', 'щ'),
-        array('ивш', 'ывш', 'ующ')
-    );
+    protected static $participle = [
+        ['ем', 'нн', 'вш', 'ющ', 'щ'],
+        ['ивш', 'ывш', 'ующ']
+    ];
 
-    protected static $reflexive = array('ся', 'сь');
+    protected static $reflexive = ['ся', 'сь'];
 
-    protected static $verb = array(
-        array('ешь', 'нно', 'ете', 'йте', 'ла', 'на', 'ли', 'й', 'л', 'ем', 'н', 'ло', 'но', 'ет', 'ют', 'ны', 'ть'),
-        array(
+    protected static $verb = [
+        ['ешь', 'нно', 'ете', 'йте', 'ла', 'на', 'ли', 'й', 'л', 'ем', 'н', 'ло', 'но', 'ет', 'ют', 'ны', 'ть'],
+        [
             'уйте', 'ило', 'ыло', 'ено','ила', 'ыла', 'ена', 'ейте', 'ены', 'ить', 'ыть', 'ишь', 'ите', 'или', 'ыли',
             'ует', 'уют', 'ей', 'уй', 'ил', 'ыл', 'им', 'ым', 'ен', 'ят', 'ит', 'ыт', 'ую', 'ю'
-        )
-    );
+        ]
+    ];
 
-    protected static $noun = array(
+    protected static $noun = [
         'иями', 'ями', 'ами', 'ией', 'иям', 'ием', 'иях', 'ев', 'ов', 'ие', 'ье', 'еи', 'ии', 'ей', 'ой', 'ий', 'ям',
         'ем', 'ам', 'ом', 'ах', 'ях', 'ию', 'ью', 'ия', 'ья', 'я', 'а', 'е', 'ы', 'ь', 'и', 'о', 'у', 'й', 'ю'
-    );
+    ];
 
-    protected static $superlative = array('ейше', 'ейш');
+    protected static $superlative = ['ейше', 'ейш'];
 
-    protected static $derivational = array('ость', 'ост');
+    protected static $derivational = ['ость', 'ост'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -82,75 +82,54 @@ public function stem($word)
      * Otherwise try and remove a REFLEXIVE ending, and then search in turn for (1) an ADJECTIVAL, (2) a VERB or (3) a NOUN ending.
      * As soon as one of the endings (1) to (3) is found remove it, and terminate step 1.
      */
-    private function step1()
+    private function step1(): bool
     {
         // Search for a PERFECTIVE GERUND ending.
         // group 1
-        if ( ($position = $this->searchIfInRv(self::$perfectiveGerund[0])) !== false) {
-            if ( ($this->inRv($position)) && ($this->checkGroup1($position)) ) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(self::$perfectiveGerund[0]) !== false && ($this->inRv($position) && $this->checkGroup1($position))) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
 
         // group 2
-        if ( ($position = $this->searchIfInRv(self::$perfectiveGerund[1])) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(self::$perfectiveGerund[1]) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
 
         // Otherwise try and remove a REFLEXIVE ending
-        if ( ($position = $this->searchIfInRv(self::$reflexive)) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-            }
+        if ( $position = $this->searchIfInRv(self::$reflexive) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
         }
 
         // then search in turn for (1) an ADJECTIVAL, (2) a VERB or (3) a NOUN ending.
         // As soon as one of the endings (1) to (3) is found remove it, and terminate step 1.
-        if ( ($position = $this->searchIfInRv(self::$adjective)) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-
-                if ( ($position2 = $this->search(self::$participle[0])) !== false) {
-                    if ( ($this->inRv($position2)) && ($this->checkGroup1($position2)) ) {
-                        $this->word = UTF8::substr($this->word, 0, $position2);
-                        return true;
-                    }
-                }
-
-                if ( ($position2 = $this->search(self::$participle[1])) !== false) {
-                    if ($this->inRv($position2)) {
-                        $this->word = UTF8::substr($this->word, 0, $position2);
-                        return true;
-                    }
-                }
-
+        if ($position = $this->searchIfInRv(self::$adjective) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            if ($position2 = $this->search(self::$participle[0]) !== false && ($this->inRv($position2) && $this->checkGroup1($position2))) {
+                $this->word = UTF8::substr($this->word, 0, $position2);
                 return true;
             }
-        }
-
-        if ( ($position = $this->searchIfInRv(self::$verb[0])) !== false) {
-            if ( ($this->inRv($position)) && ($this->checkGroup1($position)) ) {
-                $this->word = UTF8::substr($this->word, 0, $position);
+            if ($position2 = $this->search(self::$participle[1]) !== false && $this->inRv($position2)) {
+                $this->word = UTF8::substr($this->word, 0, $position2);
                 return true;
             }
+            return true;
         }
 
-        if ( ($position = $this->searchIfInRv(self::$verb[1])) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(self::$verb[0]) !== false && ($this->inRv($position) && $this->checkGroup1($position))) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
 
-        if ( ($position = $this->searchIfInRv(self::$noun)) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(self::$verb[1]) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
+        }
+
+        if ($position = $this->searchIfInRv(self::$noun) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
 
         return false;
@@ -159,13 +138,11 @@ private function step1()
     /**
      * Step 2: If the word ends with и (i), remove it.
      */
-    private function step2()
+    private function step2(): bool
     {
-        if ( ($position = $this->searchIfInRv(array('и'))) !== false) {
-            if ($this->inRv($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(['и']) !== false && $this->inRv($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
         return false;
     }
@@ -174,21 +151,20 @@ private function step2()
      * Step 3: Search for a DERIVATIONAL ending in R2 (i.e. the entire ending must lie in R2),
      * and if one is found, remove it.
      */
-    private function step3()
+    private function step3(): ?bool
     {
-        if ( ($position = $this->searchIfInRv(self::$derivational)) !== false) {
-            if ($this->inR2($position)) {
-                $this->word = UTF8::substr($this->word, 0, $position);
-                return true;
-            }
+        if ($position = $this->searchIfInRv(self::$derivational) !== false && $this->inR2($position)) {
+            $this->word = UTF8::substr($this->word, 0, $position);
+            return true;
         }
+        return null;
     }
 
     /**
      *  Step 4: (1) Undouble н (n), or, (2) if the word ends with a SUPERLATIVE ending, remove it
      *  and undouble н (n), or (3) if the word ends ь (') (soft sign) remove it.
      */
-    private function step4()
+    private function step4(): ?bool
     {
         // (2) if the word ends with a SUPERLATIVE ending, remove it
         if ( ($position = $this->searchIfInRv(self::$superlative)) !== false) {
@@ -196,22 +172,23 @@ private function step4()
         }
 
         // (1) Undouble н (n)
-        if ( ($position = $this->searchIfInRv(array('нн'))) !== false) {
+        if ( ($position = $this->searchIfInRv(['нн'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, ($position+1));
             return true;
         }
 
         // (3) if the word ends ь (') (soft sign) remove it
-        if ( ($position = $this->searchIfInRv(array('ь'))) !== false) {
+        if ( ($position = $this->searchIfInRv(['ь'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
+        return null;
     }
 
     /**
      *  In any word, RV is the region after the first vowel, or the end of the word if it contains no vowel.
      */
-    protected function rv()
+    protected function rv(): bool
     {
         $length = UTF8::strlen($this->word);
 
@@ -243,10 +220,6 @@ private function checkGroup1($position)
         }
 
         $letter = UTF8::substr($this->word, ($position - 1), 1);
-
-        if ($letter == 'а' || $letter == 'я') {
-            return true;
-        }
-        return false;
+        return $letter == 'а' || $letter == 'я';
     }
 }
diff --git a/src/Stemmer/Spanish.php b/src/Stemmer/Spanish.php
index 190f761..acd8084 100644
--- a/src/Stemmer/Spanish.php
+++ b/src/Stemmer/Spanish.php
@@ -15,12 +15,12 @@ class Spanish extends Stem
     /**
      * All spanish vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'á', 'é', 'í', 'ó', 'ú', 'ü');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'á', 'é', 'í', 'ó', 'ú', 'ü'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -39,11 +39,11 @@ public function stem($word)
         $this->step1();
 
         // Do step 2a if no ending was removed by step 1.
-        if ($this->word == $word) {
+        if ($this->word === $word) {
             $this->step2a();
 
             // Do Step 2b if step 2a was done, but failed to remove a suffix.
-            if ($this->word == $word) {
+            if ($this->word === $word) {
                 $this->step2b();
             }
         }
@@ -68,14 +68,14 @@ public function stem($word)
      *  in RV. In the case of (c), yendo must lie in RV, but the preceding u can be outside it.
      *  In the case of (a), deletion is followed by removing the acute accent (for example, haciéndola -> haciendo).
      */
-    private function step0()
+    private function step0(): bool
     {
-        if ( ($position = $this->searchIfInRv(array('selas', 'selos', 'las', 'los', 'les', 'nos', 'selo', 'sela', 'me', 'se', 'la', 'le', 'lo' ))) != false) {
+        if ( ($position = $this->searchIfInRv(['selas', 'selos', 'las', 'los', 'les', 'nos', 'selo', 'sela', 'me', 'se', 'la', 'le', 'lo' ])) != false) {
             $suffixe = UTF8::substr($this->word, $position);
 
             // a
-            $a = array('iéndo', 'ándo', 'ár', 'ér', 'ír');
-            $a = array_map(function($item) use ($suffixe) {
+            $a = ['iéndo', 'ándo', 'ár', 'ér', 'ír'];
+            $a = array_map(function(string $item) use ($suffixe): string {
                 return $item . $suffixe;
             }, $a);
 
@@ -89,8 +89,8 @@ private function step0()
             }
 
             // b
-            $b = array('iendo', 'ando', 'ar', 'er', 'ir');
-            $b = array_map(function($item) use ($suffixe) {
+            $b = ['iendo', 'ando', 'ar', 'er', 'ir'];
+            $b = array_map(function(string $item) use ($suffixe): string {
                 return $item . $suffixe;
             }, $b);
 
@@ -100,7 +100,7 @@ private function step0()
             }
 
             // c
-            if ( ($position2 = $this->searchIfInRv(array('yendo' . $suffixe))) != false) {
+            if ( ($position2 = $this->searchIfInRv(['yendo' . $suffixe])) != false) {
                 $before = UTF8::substr($this->word, ($position2-1), 1);
                 if ( (isset($before)) && ($before == 'u') ) {
                     $this->word = UTF8::substr($this->word, 0, $position);
@@ -115,14 +115,14 @@ private function step0()
     /**
      * Step 1
      */
-    private function step1()
+    private function step1(): bool
     {
         // anza   anzas   ico   ica   icos   icas   ismo   ismos   able   ables   ible   ibles   ista
         // istas   oso   osa   osos   osas   amiento   amientos   imiento   imientos
         //      delete if in R2
-        if ( ($position = $this->search(array(
+        if ( ($position = $this->search([
             'imientos', 'imiento', 'amientos', 'amiento', 'osas', 'osos', 'osa', 'oso', 'istas', 'ista', 'ibles',
-            'ible', 'ables', 'able', 'ismos', 'ismo', 'icas', 'icos', 'ica', 'ico', 'anzas', 'anza'))) != false) {
+            'ible', 'ables', 'able', 'ismos', 'ismo', 'icas', 'icos', 'ica', 'ico', 'anzas', 'anza'])) != false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
@@ -133,14 +133,14 @@ private function step1()
         // adora   ador   ación   adoras   adores   aciones   ante   antes   ancia   ancias
         //      delete if in R2
         //      if preceded by ic, delete if in R2
-        if ( ($position = $this->search(array(
-            'adoras', 'adora', 'aciones', 'ación', 'adores', 'ador', 'antes', 'ante', 'ancias', 'ancia'))) != false) {
+        if ( ($position = $this->search([
+            'adoras', 'adora', 'aciones', 'ación', 'adores', 'ador', 'antes', 'ante', 'ancias', 'ancia'])) != false) {
 
             if ($this->inR2($position)) {
                 $this->word = UTF8::substr($this->word, 0, $position);
             }
 
-            if ( ($position2 = $this->searchIfInR2(array('ic')))) {
+            if ( ($position2 = $this->searchIfInR2(['ic']))) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -148,7 +148,7 @@ private function step1()
 
         // logía   logías
         //      replace with log if in R2
-        if ( ($position = $this->search(array('logías', 'logía'))) != false) {
+        if ( ($position = $this->search(['logías', 'logía'])) != false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(logías|logía)$#u', 'log', $this->word);
             }
@@ -157,7 +157,7 @@ private function step1()
 
         // ución   uciones
         //      replace with u if in R2
-        if ( ($position = $this->search(array('uciones', 'ución'))) != false) {
+        if ( ($position = $this->search(['uciones', 'ución'])) != false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(uciones|ución)$#u', 'u', $this->word);
             }
@@ -166,7 +166,7 @@ private function step1()
 
         // encia   encias
         //      replace with ente if in R2
-        if ( ($position = $this->search(array('encias', 'encia'))) != false) {
+        if ( ($position = $this->search(['encias', 'encia'])) != false) {
             if ($this->inR2($position)) {
                 $this->word = preg_replace('#(encias|encia)$#u', 'ente', $this->word);
             }
@@ -177,7 +177,7 @@ private function step1()
         //      delete if in R1
         //      if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
         //      if preceded by os, ic or ad, delete if in R2
-        if ( ($position = $this->search(array('amente'))) != false) {
+        if ( ($position = $this->search(['amente'])) != false) {
 
             // delete if in R1
             if ($this->inR1($position)) {
@@ -185,14 +185,14 @@ private function step1()
             }
 
             // if preceded by iv, delete if in R2 (and if further preceded by at, delete if in R2), otherwise,
-            if ( ($position2 = $this->searchIfInR2(array('iv'))) !== false) {
+            if ( ($position2 = $this->searchIfInR2(['iv'])) !== false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
-                if ( ($position3 = $this->searchIfInR2(array('at'))) !== false) {
+                if ( ($position3 = $this->searchIfInR2(['at'])) !== false) {
                     $this->word = UTF8::substr($this->word, 0, $position3);
                 }
 
             // if preceded by os, ic or ad, delete if in R2
-            } elseif ( ($position4 = $this->searchIfInR2(array('os', 'ic', 'ad'))) != false) {
+            } elseif ( ($position4 = $this->searchIfInR2(['os', 'ic', 'ad'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position4);
             }
             return true;
@@ -201,7 +201,7 @@ private function step1()
         // mente
         //      delete if in R2
         //      if preceded by ante, able or ible, delete if in R2
-        if ( ($position = $this->search(array('mente'))) != false) {
+        if ( ($position = $this->search(['mente'])) != false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -209,7 +209,7 @@ private function step1()
             }
 
             // if preceded by ante, able or ible, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('ante', 'able', 'ible'))) != false) {
+            if ( ($position2 = $this->searchIfInR2(['ante', 'able', 'ible'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -218,7 +218,7 @@ private function step1()
         // idad   idades
         //      delete if in R2
         //      if preceded by abil, ic or iv, delete if in R2
-        if ( ($position = $this->search(array('idades', 'idad'))) != false) {
+        if ( ($position = $this->search(['idades', 'idad'])) != false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -226,7 +226,7 @@ private function step1()
             }
 
             // if preceded by abil, ic or iv, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('abil', 'ic', 'iv'))) != false) {
+            if ( ($position2 = $this->searchIfInR2(['abil', 'ic', 'iv'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -235,7 +235,7 @@ private function step1()
         // iva   ivo   ivas   ivos
         //      delete if in R2
         //      if preceded by at, delete if in R2
-        if ( ($position = $this->search(array('ivas', 'ivos', 'iva', 'ivo'))) != false) {
+        if ( ($position = $this->search(['ivas', 'ivos', 'iva', 'ivo'])) != false) {
 
             // delete if in R2
             if ($this->inR2($position)) {
@@ -243,7 +243,7 @@ private function step1()
             }
 
             // if preceded by at, delete if in R2
-            if ( ($position2 = $this->searchIfInR2(array('at'))) != false) {
+            if ( ($position2 = $this->searchIfInR2(['at'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, $position2);
             }
             return true;
@@ -255,12 +255,12 @@ private function step1()
     /**
      * Step 2a: Verb suffixes beginning y
      */
-    private function step2a()
+    private function step2a(): bool
     {
         // if found, delete if preceded by u
         // (Note that the preceding u need not be in RV.)
-        if ( ($position = $this->searchIfInRv(array(
-            'yamos', 'yendo', 'yeron', 'yan', 'yen', 'yais', 'yas', 'yes', 'yo', 'yó', 'ya', 'ye'))) != false) {
+        if ( ($position = $this->searchIfInRv([
+            'yamos', 'yendo', 'yeron', 'yan', 'yen', 'yais', 'yas', 'yes', 'yo', 'yó', 'ya', 'ye'])) != false) {
 
             $before = UTF8::substr($this->word, ($position-1), 1);
             if ( (isset($before)) && ($before == 'u') ) {
@@ -276,10 +276,10 @@ private function step2a()
      * Step 2b: Other verb suffixes
      *      Search for the longest among the following suffixes in RV, and perform the action indicated.
      */
-    private function step2b()
+    private function step2b(): ?bool
     {
         //      delete
-        if ( ($position = $this->searchIfInRv(array(
+        if ( ($position = $this->searchIfInRv([
             'iésemos', 'iéramos', 'ábamos', 'iríamos', 'eríamos', 'aríamos', 'áramos', 'ásemos', 'eríais',
             'aremos', 'eremos', 'iremos', 'asteis', 'ieseis', 'ierais', 'isteis', 'aríais',
             'irían', 'aréis', 'erían', 'erías', 'eréis', 'iréis', 'irías', 'ieran', 'iesen', 'ieron', 'iendo', 'ieras',
@@ -288,44 +288,45 @@ private function step2b()
             'iera', 'iese', 'aste', 'iste', 'aban', 'aran', 'asen', 'aron', 'ando', 'abas', 'adas', 'idas', 'ases', 'aras',
             'aré', 'erá', 'eré', 'áis', 'ías', 'irá', 'iré', 'aba', 'ían', 'ada', 'ara', 'ase', 'ida', 'ado', 'ido', 'ará',
             'ad', 'ed', 'id', 'ís', 'ió', 'ar', 'er', 'ir', 'as', 'ía', 'an'
-        ))) != false) {
+        ])) != false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         // en   es   éis   emos
         //      delete, and if preceded by gu delete the u (the gu need not be in RV)
-        if ( ($position = $this->searchIfInRv(array('éis', 'emos', 'en', 'es'))) != false) {
+        if ( ($position = $this->searchIfInRv(['éis', 'emos', 'en', 'es'])) != false) {
             $this->word = UTF8::substr($this->word, 0, $position);
 
-            if ( ($position2 = $this->search(array('gu'))) != false) {
+            if ( ($position2 = $this->search(['gu'])) != false) {
                 $this->word = UTF8::substr($this->word, 0, ($position2+1));
             }
 
 
             return true;
         }
+        return null;
     }
 
     /**
      * Step 3: residual suffix
      * Search for the longest among the following suffixes in RV, and perform the action indicated.
      */
-    private function step3()
+    private function step3(): bool
     {
         // os   a   o   á   í   ó
         //      delete if in RV
-        if ( ($position = $this->searchIfInRv(array('os', 'a', 'o', 'á', 'í', 'ó'))) != false) {
+        if ( ($position = $this->searchIfInRv(['os', 'a', 'o', 'á', 'í', 'ó'])) != false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         // e   é
         //      delete if in RV, and if preceded by gu with the u in RV delete the u
-        if ( ($position = $this->searchIfInRv(array('e', 'é'))) != false) {
+        if ( ($position = $this->searchIfInRv(['e', 'é'])) != false) {
             $this->word = UTF8::substr($this->word, 0, $position);
 
-            if ( ($position2 = $this->searchIfInRv(array('u'))) != false) {
+            if ( ($position2 = $this->searchIfInRv(['u'])) != false) {
                 $before = UTF8::substr($this->word, ($position2-1), 1);
                 if ( (isset($before)) && ($before == 'g') ) {
                     $this->word = UTF8::substr($this->word, 0, $position2);
@@ -341,8 +342,8 @@ private function step3()
      * And finally:
      * Remove acute accents
      */
-    private function finish()
+    private function finish(): void
     {
-        $this->word = str_replace(array('á', 'í', 'ó', 'é', 'ú'), array('a', 'i', 'o', 'e', 'u'), $this->word);
+        $this->word = str_replace(['á', 'í', 'ó', 'é', 'ú'], ['a', 'i', 'o', 'e', 'u'], $this->word);
     }
 }
diff --git a/src/Stemmer/Stem.php b/src/Stemmer/Stem.php
index 0c6f148..11f4e29 100644
--- a/src/Stemmer/Stem.php
+++ b/src/Stemmer/Stem.php
@@ -6,7 +6,7 @@
 
 abstract class Stem implements Stemmer
 {
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y'];
 
     /**
      * helper, contains stringified list of vowels
@@ -112,7 +112,7 @@ protected function search($suffixes, $offset = 0)
      */
     protected function r1()
     {
-        list($this->r1Index, $this->r1) = $this->rx($this->word);
+        [$this->r1Index, $this->r1] = $this->rx($this->word);
     }
 
     /**
@@ -120,7 +120,7 @@ protected function r1()
      */
     protected function r2()
     {
-        list($index, $value) = $this->rx($this->r1);
+        [$index, $value] = $this->rx($this->r1);
 
         $this->r2 = $value;
         $this->r2Index = $this->r1Index + $index;
@@ -132,7 +132,7 @@ protected function r2()
      * R1 : $in = $this->word
      * R2 : $in = R1
      */
-    protected function rx($in)
+    protected function rx(string $in)
     {
         $length = UTF8::strlen($in);
 
@@ -141,7 +141,7 @@ protected function rx($in)
         $index = $length;
 
         // we search all vowels
-        $vowels = array();
+        $vowels = [];
         for ($i=0; $i<$length; $i++) {
             $letter = UTF8::substr($in, $i, 1);
             if (in_array($letter, static::$vowels)) {
@@ -162,7 +162,7 @@ protected function rx($in)
             }
         }
 
-        return array($index, $value);
+        return [$index, $value];
     }
 
     /**
@@ -217,5 +217,6 @@ protected function rv()
             $this->rvIndex = 3;
             return true;
         }
+        return null;
     }
 }
diff --git a/src/Stemmer/Stemmer.php b/src/Stemmer/Stemmer.php
index b43b0f1..cf04660 100644
--- a/src/Stemmer/Stemmer.php
+++ b/src/Stemmer/Stemmer.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Wamania\Snowball\Stemmer;
 
 /**
diff --git a/src/Stemmer/Swedish.php b/src/Stemmer/Swedish.php
index 32352ef..a409699 100644
--- a/src/Stemmer/Swedish.php
+++ b/src/Stemmer/Swedish.php
@@ -15,12 +15,12 @@ class Swedish extends Stem
     /**
      * All swedish vowels
      */
-    protected static $vowels = array('a', 'e', 'i', 'o', 'u', 'y', 'ä', 'å', 'ö');
+    protected static $vowels = ['a', 'e', 'i', 'o', 'u', 'y', 'ä', 'å', 'ö'];
 
     /**
      * {@inheritdoc}
      */
-    public function stem($word)
+    public function stem($word): string
     {
         // we do ALL in UTF-8
         if (!UTF8::is_utf8($word)) {
@@ -51,51 +51,51 @@ public function stem($word)
      * b   c   d   f   g   h   j   k   l   m   n   o   p   r   t   v   y
      *
      * @param string $ending
-     * @return boolean
      */
-    private function hasValidSEnding($word)
+    private function hasValidSEnding(string $word): bool
     {
         $lastLetter = UTF8::substr($word, -1, 1);
-        return in_array($lastLetter, array('b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y'));
+        return in_array($lastLetter, ['b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'r', 't', 'v', 'y']);
     }
 
     /**
      * Step 1
      * Search for the longest among the following suffixes in R1, and perform the action indicated.
      */
-    private function step1()
+    private function step1(): ?bool
     {
         // a   arna   erna   heterna   orna   ad   e   ade   ande   arne   are   aste   en   anden   aren   heten
         // ern   ar   er   heter   or   as   arnas   ernas   ornas   es   ades   andes   ens   arens   hetens
         // erns   at   andet   het   ast
         //      delete
-        if ( ($position = $this->searchIfInR1(array(
+        if ( ($position = $this->searchIfInR1([
             'heterna', 'hetens', 'ornas', 'andes', 'arnas', 'heter', 'ernas', 'anden', 'heten', 'andet', 'arens',
             'orna', 'arna', 'erna', 'aren', 'ande', 'ades', 'arne', 'erns', 'aste', 'ade', 'ern', 'het',
             'ast', 'are', 'ens', 'or', 'es', 'ad', 'en', 'at', 'ar', 'as', 'er', 'a', 'e'
-        ))) !== false) {
+        ])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         //  s
         //      delete if preceded by a valid s-ending
-        if ( ($position = $this->searchIfInR1(array('s'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['s'])) !== false) {
             $word = UTF8::substr($this->word, 0, $position);
             if ($this->hasValidSEnding($word)) {
                 $this->word = $word;
             }
         }
+        return null;
     }
 
     /**
      * Step 2
      * Search for one of the following suffixes in R1, and if found delete the last letter.
      */
-    private function step2()
+    private function step2(): void
     {
         // dd   gd   nn   dt   gt   kt   tt
-        if ($this->searchIfInR1(array('dd', 'gd', 'nn', 'dt', 'gt', 'kt', 'tt')) !== false) {
+        if ($this->searchIfInR1(['dd', 'gd', 'nn', 'dt', 'gt', 'kt', 'tt']) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
         }
     }
@@ -104,27 +104,28 @@ private function step2()
      * Step 3:
      * Search for the longest among the following suffixes in R1, and perform the action indicated.
      */
-    private function step3()
+    private function step3(): ?bool
     {
         // lig   ig   els
         //      delete
-        if ( ($position = $this->searchIfInR1(array('lig', 'ig', 'els'))) !== false) {
+        if ( ($position = $this->searchIfInR1(['lig', 'ig', 'els'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, $position);
             return true;
         }
 
         // löst
         //      replace with lös
-        if ( ($this->searchIfInR1(array('löst'))) !== false) {
+        if ( ($this->searchIfInR1(['löst'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
             return true;
         }
 
         // fullt
         //      replace with full
-        if ( ($this->searchIfInR1(array('fullt'))) !== false) {
+        if ( ($this->searchIfInR1(['fullt'])) !== false) {
             $this->word = UTF8::substr($this->word, 0, -1);
             return true;
         }
+        return null;
     }
 }
diff --git a/src/StemmerManager.php b/src/StemmerManager.php
index e31acc3..3deb45d 100644
--- a/src/StemmerManager.php
+++ b/src/StemmerManager.php
@@ -5,12 +5,7 @@
 class StemmerManager
 {
     /** @var array */
-    private $stemmers;
-
-    public function __construct()
-    {
-        $this->stemmers = [];
-    }
+    private $stemmers = [];
 
     /**
      * @throws NotFoundException
diff --git a/test/CatalanTest.php b/test/CatalanTest.php
index b410590..4821c2a 100644
--- a/test/CatalanTest.php
+++ b/test/CatalanTest.php
@@ -9,7 +9,7 @@ class CatalanTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Catalan();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/ca.txt');
     }
diff --git a/test/CsvFileIterator.php b/test/CsvFileIterator.php
index bf1ed17..241217c 100644
--- a/test/CsvFileIterator.php
+++ b/test/CsvFileIterator.php
@@ -10,7 +10,7 @@ class CsvFileIterator implements \Iterator
     public function __construct($file)
     {
         if (! ($this->file = fopen($file, 'r'))) {
-            die('Can\'t open file '.$this->file)."\n";
+            die('Can\'t open file '.$this->file);
         }
     }
 
@@ -20,7 +20,7 @@ public function __destruct()
     }
 
     #[\ReturnTypeWillChange]
-    public function rewind()
+    public function rewind(): void
     {
         rewind($this->file);
         //$this->current = fgetcsv($this->file, null, "\t");
@@ -52,7 +52,7 @@ public function current()
     }
 
     #[\ReturnTypeWillChange]
-    public function next()
+    public function next(): void
     {
         $line = fgets($this->file);
         $current = explode(' ', $line);
diff --git a/test/DanishTest.php b/test/DanishTest.php
index b846d72..4f08849 100644
--- a/test/DanishTest.php
+++ b/test/DanishTest.php
@@ -9,7 +9,7 @@ class DanishTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Danish();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/dk.txt');
     }
diff --git a/test/DutchTest.php b/test/DutchTest.php
index 6e21f8c..ea51931 100644
--- a/test/DutchTest.php
+++ b/test/DutchTest.php
@@ -9,7 +9,7 @@ class DutchTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Dutch();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/nl.txt');
     }
diff --git a/test/EnglishTest.php b/test/EnglishTest.php
index a38fb0f..85b617e 100644
--- a/test/EnglishTest.php
+++ b/test/EnglishTest.php
@@ -9,7 +9,7 @@ class EnglishTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new English();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/en.txt');
     }
diff --git a/test/FactoryTest.php b/test/FactoryTest.php
index 73dd5f2..ced8ae9 100644
--- a/test/FactoryTest.php
+++ b/test/FactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Wamania\Snowball\Tests;
 
 use PHPUnit\Framework\TestCase;
@@ -7,52 +9,52 @@
 
 class FactoryTest extends TestCase
 {
-    public function testFactory()
+    public function testFactory(): void
     {
         $isoCodes = [
-            'ca' => 'Wamania\\Snowball\\Stemmer\\Catalan',
-            'cat' => 'Wamania\\Snowball\\Stemmer\\Catalan',
-            'catalan' => 'Wamania\\Snowball\\Stemmer\\Catalan',
-            'da' => 'Wamania\\Snowball\\Stemmer\\Danish',
-            'dan' => 'Wamania\\Snowball\\Stemmer\\Danish',
-            'danish' => 'Wamania\\Snowball\\Stemmer\\Danish',
-            'nl' => 'Wamania\\Snowball\\Stemmer\\Dutch',
-            'dut' => 'Wamania\\Snowball\\Stemmer\\Dutch',
-            'nld' => 'Wamania\\Snowball\\Stemmer\\Dutch',
-            'dutch' => 'Wamania\\Snowball\\Stemmer\\Dutch',
-            'en' => 'Wamania\\Snowball\\Stemmer\\English',
-            'eng' => 'Wamania\\Snowball\\Stemmer\\English',
-            'english' => 'Wamania\\Snowball\\Stemmer\\English',
-            'fr' => 'Wamania\\Snowball\\Stemmer\\French',
-            'fre' => 'Wamania\\Snowball\\Stemmer\\French',
-            'fra' => 'Wamania\\Snowball\\Stemmer\\French',
-            'french' => 'Wamania\\Snowball\\Stemmer\\French',
-            'de' => 'Wamania\\Snowball\\Stemmer\\German',
-            'deu' => 'Wamania\\Snowball\\Stemmer\\German',
-            'ger' => 'Wamania\\Snowball\\Stemmer\\German',
-            'german' => 'Wamania\\Snowball\\Stemmer\\German',
-            'it' => 'Wamania\\Snowball\\Stemmer\\Italian',
-            'ita' => 'Wamania\\Snowball\\Stemmer\\Italian',
-            'italian' => 'Wamania\\Snowball\\Stemmer\\Italian',
-            'no' => 'Wamania\\Snowball\\Stemmer\\Norwegian',
-            'nor' => 'Wamania\\Snowball\\Stemmer\\Norwegian',
-            'norwegian' => 'Wamania\\Snowball\\Stemmer\\Norwegian',
-            'pt' => 'Wamania\\Snowball\\Stemmer\\Portuguese',
-            'por' => 'Wamania\\Snowball\\Stemmer\\Portuguese',
-            'portuguese' => 'Wamania\\Snowball\\Stemmer\\Portuguese',
-            'ro' => 'Wamania\\Snowball\\Stemmer\\Romanian',
-            'rum' => 'Wamania\\Snowball\\Stemmer\\Romanian',
-            'ron' => 'Wamania\\Snowball\\Stemmer\\Romanian',
-            'romanian' => 'Wamania\\Snowball\\Stemmer\\Romanian',
-            'ru' => 'Wamania\\Snowball\\Stemmer\\Russian',
-            'rus' => 'Wamania\\Snowball\\Stemmer\\Russian',
-            'russian' => 'Wamania\\Snowball\\Stemmer\\Russian',
-            'es' => 'Wamania\\Snowball\\Stemmer\\Spanish',
-            'spa' => 'Wamania\\Snowball\\Stemmer\\Spanish',
-            'spanish' => 'Wamania\\Snowball\\Stemmer\\Spanish',
-            'sv' => 'Wamania\\Snowball\\Stemmer\\Swedish',
-            'swe' => 'Wamania\\Snowball\\Stemmer\\Swedish',
-            'swedish' => 'Wamania\\Snowball\\Stemmer\\Swedish',
+            'ca' => \Wamania\Snowball\Stemmer\Catalan::class,
+            'cat' => \Wamania\Snowball\Stemmer\Catalan::class,
+            'catalan' => \Wamania\Snowball\Stemmer\Catalan::class,
+            'da' => \Wamania\Snowball\Stemmer\Danish::class,
+            'dan' => \Wamania\Snowball\Stemmer\Danish::class,
+            'danish' => \Wamania\Snowball\Stemmer\Danish::class,
+            'nl' => \Wamania\Snowball\Stemmer\Dutch::class,
+            'dut' => \Wamania\Snowball\Stemmer\Dutch::class,
+            'nld' => \Wamania\Snowball\Stemmer\Dutch::class,
+            'dutch' => \Wamania\Snowball\Stemmer\Dutch::class,
+            'en' => \Wamania\Snowball\Stemmer\English::class,
+            'eng' => \Wamania\Snowball\Stemmer\English::class,
+            'english' => \Wamania\Snowball\Stemmer\English::class,
+            'fr' => \Wamania\Snowball\Stemmer\French::class,
+            'fre' => \Wamania\Snowball\Stemmer\French::class,
+            'fra' => \Wamania\Snowball\Stemmer\French::class,
+            'french' => \Wamania\Snowball\Stemmer\French::class,
+            'de' => \Wamania\Snowball\Stemmer\German::class,
+            'deu' => \Wamania\Snowball\Stemmer\German::class,
+            'ger' => \Wamania\Snowball\Stemmer\German::class,
+            'german' => \Wamania\Snowball\Stemmer\German::class,
+            'it' => \Wamania\Snowball\Stemmer\Italian::class,
+            'ita' => \Wamania\Snowball\Stemmer\Italian::class,
+            'italian' => \Wamania\Snowball\Stemmer\Italian::class,
+            'no' => \Wamania\Snowball\Stemmer\Norwegian::class,
+            'nor' => \Wamania\Snowball\Stemmer\Norwegian::class,
+            'norwegian' => \Wamania\Snowball\Stemmer\Norwegian::class,
+            'pt' => \Wamania\Snowball\Stemmer\Portuguese::class,
+            'por' => \Wamania\Snowball\Stemmer\Portuguese::class,
+            'portuguese' => \Wamania\Snowball\Stemmer\Portuguese::class,
+            'ro' => \Wamania\Snowball\Stemmer\Romanian::class,
+            'rum' => \Wamania\Snowball\Stemmer\Romanian::class,
+            'ron' => \Wamania\Snowball\Stemmer\Romanian::class,
+            'romanian' => \Wamania\Snowball\Stemmer\Romanian::class,
+            'ru' => \Wamania\Snowball\Stemmer\Russian::class,
+            'rus' => \Wamania\Snowball\Stemmer\Russian::class,
+            'russian' => \Wamania\Snowball\Stemmer\Russian::class,
+            'es' => \Wamania\Snowball\Stemmer\Spanish::class,
+            'spa' => \Wamania\Snowball\Stemmer\Spanish::class,
+            'spanish' => \Wamania\Snowball\Stemmer\Spanish::class,
+            'sv' => \Wamania\Snowball\Stemmer\Swedish::class,
+            'swe' => \Wamania\Snowball\Stemmer\Swedish::class,
+            'swedish' => \Wamania\Snowball\Stemmer\Swedish::class,
         ];
 
         foreach ($isoCodes as $isoCode => $classname) {
diff --git a/test/FinnishTest.php b/test/FinnishTest.php
index 17a6c33..385d581 100644
--- a/test/FinnishTest.php
+++ b/test/FinnishTest.php
@@ -9,7 +9,7 @@ class FinnishTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Finnish();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
 		$this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/fi.txt');
     }
diff --git a/test/FrenchTest.php b/test/FrenchTest.php
index a985d2a..69d04ad 100644
--- a/test/FrenchTest.php
+++ b/test/FrenchTest.php
@@ -9,7 +9,7 @@ class FrenchTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new French();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/fr.txt');
     }
diff --git a/test/GermanTest.php b/test/GermanTest.php
index 3bec53d..9e50aba 100644
--- a/test/GermanTest.php
+++ b/test/GermanTest.php
@@ -9,7 +9,7 @@ class GermanTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new German();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/de.txt');
     }
diff --git a/test/ItalianTest.php b/test/ItalianTest.php
index c77d8ac..a80d763 100644
--- a/test/ItalianTest.php
+++ b/test/ItalianTest.php
@@ -9,7 +9,7 @@ class ItalianTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Italian();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/it.txt');
     }
diff --git a/test/ManagerTest.php b/test/ManagerTest.php
index cfe0e9a..46a28ab 100644
--- a/test/ManagerTest.php
+++ b/test/ManagerTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Wamania\Snowball\Tests;
 
 use PHPUnit\Framework\TestCase;
@@ -7,7 +9,7 @@
 
 class ManagerTest extends TestCase
 {
-    public function testManager()
+    public function testManager(): void
     {
         $stemmerManager = new StemmerManager();
 
diff --git a/test/NorwegianTest.php b/test/NorwegianTest.php
index 6265d58..8e33fd0 100644
--- a/test/NorwegianTest.php
+++ b/test/NorwegianTest.php
@@ -9,7 +9,7 @@ class NorwegianTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Norwegian();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/no.txt');
     }
diff --git a/test/PortugueseTest.php b/test/PortugueseTest.php
index 6cf8851..6606cc1 100644
--- a/test/PortugueseTest.php
+++ b/test/PortugueseTest.php
@@ -9,7 +9,7 @@ class PortugueseTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Portuguese();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/pt.txt');
     }
diff --git a/test/RomanianTest.php b/test/RomanianTest.php
index 150510b..4f86be0 100644
--- a/test/RomanianTest.php
+++ b/test/RomanianTest.php
@@ -9,7 +9,7 @@ class RomanianTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Romanian();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/ro.txt');
     }
diff --git a/test/RussianTest.php b/test/RussianTest.php
index e95a6c9..eb6d58c 100644
--- a/test/RussianTest.php
+++ b/test/RussianTest.php
@@ -9,7 +9,7 @@ class RussianTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Russian();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/ru.txt');
     }
diff --git a/test/SpanishTest.php b/test/SpanishTest.php
index 7b3cf40..f28d334 100644
--- a/test/SpanishTest.php
+++ b/test/SpanishTest.php
@@ -9,7 +9,7 @@ class SpanishTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Spanish();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/es.txt');
     }
diff --git a/test/SwedishTest.php b/test/SwedishTest.php
index f3d1f71..98a535b 100644
--- a/test/SwedishTest.php
+++ b/test/SwedishTest.php
@@ -9,7 +9,7 @@ class SwedishTest extends TestCase
     /**
      * @dataProvider load
      */
-    public function testStem($word, $stem)
+    public function testStem($word, $stem): void
     {
         $o = new Swedish();
 
@@ -18,7 +18,7 @@ public function testStem($word, $stem)
         $this->assertEquals($stem, $snowballStem);
     }
 
-    public function load()
+    public function load(): \Wamania\Snowball\Tests\CsvFileIterator
     {
         return new CsvFileIterator('test/files/sw.txt');
     }