diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index eb9acb7..90dbcaf 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -37,6 +37,11 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-${{ matrix.setup }}-php-${{ matrix.php }}-
 
+    - name: Add fig/http-message-util
+      if: matrix.setup == 'lowest' && matrix.php == '7.1'
+      run: |
+        composer require "fig/http-message-util:^1.1.5" --no-update
+
     - name: Install dependencies
       if: steps.composer-cache.outputs.cache-hit != 'true'
       run: |
diff --git a/composer.json b/composer.json
index 859b71e..2ced1b1 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "slim/slim": "^3.12.5 || ^4.15.1",
         "slim/psr7": "*",
         "php-di/php-di": "^5.4.6 || ^6.4",
-        "phpunit/phpunit": "^4.8.35 || ^5.7 || ^8.5.15"
+        "phpunit/phpunit": "^4.8.36 || ^5.7.27 || ^8.5.52"
     },
     "autoload": {
         "psr-4": {
diff --git a/tests/AbstractTestCase.php b/tests/AbstractTestCase.php
index 4f9652a..3b3fa1c 100644
--- a/tests/AbstractTestCase.php
+++ b/tests/AbstractTestCase.php
@@ -15,6 +15,7 @@
 use Slim\Http\Uri as Slim3Uri;
 use Slim\Psr7\Headers;
 use Slim\Psr7\Request;
+use Slim\Psr7\Response;
 use Slim\Psr7\Stream;
 use Slim\Psr7\Uri;
 use Slim\Pug\PugRenderer;
@@ -116,7 +117,7 @@ protected function fetch(string $path): string
         // Slim 4
         if (class_exists(Headers::class)) {
             // Run App & Emit Response
-            $response = $app->handle(new Request(
+            $response = $this->getResponse($app, new Request(
                 'GET',
                 new Uri('https', 'domain.com', 443, $path),
                 new Headers(),
@@ -164,4 +165,18 @@ private function getContents(string $path, string $file): string
 
         return $contents;
     }
+
+    private function getResponse(App $app, Request $request): Response
+    {
+        if (!method_exists($app, 'handle')) {
+            error_reporting(E_ALL ^ E_DEPRECATED);
+            $response = new Response();
+            $app->process($request, $response);
+
+            return $response;
+        }
+
+        // Run App & Emit Response
+        return $app->handle($request);
+    }
 }