diff --git a/src/DI/Container.php b/src/DI/Container.php
index 61edf727d..c51b9a367 100644
--- a/src/DI/Container.php
+++ b/src/DI/Container.php
@@ -363,4 +363,9 @@ public static function getMethodName(string $name): string
 
 		return 'createService' . str_replace('.', '__', ucfirst($name));
 	}
+
+
+	public function initialize(): void
+	{
+	}
 }
diff --git a/src/DI/PhpGenerator.php b/src/DI/PhpGenerator.php
index d928a7e37..5ba0a0776 100644
--- a/src/DI/PhpGenerator.php
+++ b/src/DI/PhpGenerator.php
@@ -66,7 +66,8 @@ public function generate(string $className): Php\ClassType
 			->setReturnType($className)
 			->setBody('return $this;');
 
-		$class->addMethod('initialize');
+		$class->addMethod('initialize')
+			->setReturnType('void');
 
 		return $class;
 	}