diff --git a/composer.json b/composer.json
index 075d817c..e62be925 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
         }
     ],
     "require": {
-        "php": "^7.4 || ^8.0",
+        "php": "^8.1",
         "symfony/filesystem": "^4.2 || ^5.0 || ^6.0",
         "psr/log": "^1.0 || ^2.0 || ^3.0"
     },
diff --git a/lib/Adapter/Composer/ComposerClassToFile.php b/lib/Adapter/Composer/ComposerClassToFile.php
index 8f4c7478..071ea16c 100644
--- a/lib/Adapter/Composer/ComposerClassToFile.php
+++ b/lib/Adapter/Composer/ComposerClassToFile.php
@@ -15,7 +15,7 @@ class ComposerClassToFile implements ClassToFile
 
     private LoggerInterface $logger;
 
-    public function __construct(ClassLoader $classLoader, LoggerInterface $logger = null)
+    public function __construct(ClassLoader $classLoader, ?LoggerInterface $logger = null)
     {
         $this->classLoader = $classLoader;
         $this->logger = $logger ?: new NullLogger();
diff --git a/tests/Unit/CompositeTransformerTest.php b/tests/Unit/CompositeTransformerTest.php
index 562c0755..dab18b0d 100644
--- a/tests/Unit/CompositeTransformerTest.php
+++ b/tests/Unit/CompositeTransformerTest.php
@@ -11,6 +11,7 @@
 use Phpactor\ClassFileConverter\Domain\ClassNameCandidates;
 use Phpactor\ClassFileConverter\Domain\FilePath;
 use Prophecy\PhpUnit\ProphecyTrait;
+use Prophecy\Prophecy\ObjectProphecy;
 
 class CompositeTransformerTest extends TestCase
 {
@@ -18,6 +19,10 @@ class CompositeTransformerTest extends TestCase
 
     private $transformer;
 
+    private ObjectProphecy $classToFile;
+
+    private ObjectProphecy $fileToClassCandidates;
+
     public function setUp(): void
     {
         $this->classToFile = $this->prophesize(ClassToFile::class);