diff --git a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
index d963445b30..9e15ca8339 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
@@ -310,7 +310,7 @@ class YamlFileLoader extends FileLoader
     /**
      * Parses a definition.
      *
-     * @param array|string $service
+     * @param array|string|null $service
      *
      * @throws InvalidArgumentException When tags are invalid
      */