diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 1562a68..a09cf0e 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -7,36 +7,54 @@ on:
     branches: [master]
 
 jobs:
-
   phpunit:
-    name: PHPUnit
+    name: PHPUnit - PHP ${{ matrix.php-version }} - ${{ matrix.dependency-versions }}
     runs-on: ubuntu-latest
 
     strategy:
       fail-fast: false
       matrix:
-        php-version:
-          - "8.0"
-          - "8.1"
-          - "8.2"
-          - "8.3"
-          - "8.4"
-        dependency-versions:
-          - "lowest"
-          - "highest"
+        php-version: ["8.1", "8.2", "8.3"]
+        dependency-versions: ["lowest", "highest"]
 
     steps:
-      - name: Checkout
+      - name: Checkout code
         uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-version }}
-          coverage: none
+          coverage: ${{ (matrix.php-version == '8.3' && matrix.dependency-versions == 'highest') && 'xdebug' || 'none' }}
+
+      - name: Cache Composer dependencies
+        uses: actions/cache@v3
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ matrix.php-version }}-composer-${{ matrix.dependency-versions }}-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-${{ matrix.php-version }}-composer-${{ matrix.dependency-versions }}-
+
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@v2
+        with:
+          dependency-versions: ${{ matrix.dependency-versions }}
 
-      - name: Install composer dependencies
-        run: composer install --prefer-dist --no-progress
+      - name: Run static analysis (PHPStan)
+        run: vendor/bin/phpstan analyse --level=5 src/
+        continue-on-error: true
 
       - name: Run PHPUnit
+        if: matrix.php-version != '8.3' || matrix.dependency-versions != 'highest'
         run: vendor/bin/phpunit
+
+      - name: Run PHPUnit with Coverage
+        if: matrix.php-version == '8.3' && matrix.dependency-versions == 'highest'
+        run: vendor/bin/phpunit --coverage-clover=coverage.xml
+
+      - name: Upload coverage to Codecov
+        if: matrix.php-version == '8.3' && matrix.dependency-versions == 'highest'
+        uses: codecov/codecov-action@v3
+        with:
+          files: ./coverage.xml
+          fail_ci_if_error: true
diff --git a/composer.json b/composer.json
index eddad93..4a7157a 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,8 @@
         "ext-mbstring": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.5.10"
+        "phpunit/phpunit": "^9.5.10",
+        "phpstan/phpstan": "^2.1"
     },
     "scripts": {
         "test": "vendor/bin/phpunit"
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..46b0f47
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,5 @@
+parameters:
+    level: 5
+    paths:
+        - src
+        - tests