diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a201cec..f54dd3e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,7 +9,7 @@ jobs:
             fail-fast: false
             matrix:
                 os: [ubuntu-latest]
-                php: [8.3, 8.2, 8.1, 8.0, 7.4, 7.3]
+                php: [8.4, 8.3, 8.2, 8.1, 8.0, 7.4, 7.3]
                 dependency-version: [prefer-lowest, prefer-stable]
 
         name: P${{ matrix.php }} - ${{ matrix.dependency-version }} - ${{ matrix.os }}
diff --git a/src/OptimizerChain.php b/src/OptimizerChain.php
index db603e3..c95b09f 100644
--- a/src/OptimizerChain.php
+++ b/src/OptimizerChain.php
@@ -62,11 +62,11 @@ public function useLogger(LoggerInterface $log)
         return $this;
     }
 
-    public function optimize(string $pathToImage, string $pathToOutput = null)
+    public function optimize(string $pathToImage, ?string $pathToOutput = null)
     {
         if ($pathToOutput) {
             $check = copy($pathToImage, $pathToOutput);
-            if($check == false) {
+            if ($check == false) {
                 throw new InvalidArgumentException("Cannot copy file");
             }
             $pathToImage = $pathToOutput;