diff --git a/src/Symfony/Component/Lock/Factory.php b/src/Symfony/Component/Lock/Factory.php
index e9fdde97e8..f35ad6d8ef 100644
--- a/src/Symfony/Component/Lock/Factory.php
+++ b/src/Symfony/Component/Lock/Factory.php
@@ -36,9 +36,9 @@ class Factory implements LoggerAwareInterface
     /**
      * Creates a lock for the given resource.
      *
-     * @param string $resource    The resource to lock
-     * @param float  $ttl         Maximum expected lock duration in seconds
-     * @param bool   $autoRelease Whether to automatically release the lock or not when the lock instance is destroyed
+     * @param string     $resource    The resource to lock
+     * @param float|null $ttl         Maximum expected lock duration in seconds
+     * @param bool       $autoRelease Whether to automatically release the lock or not when the lock instance is destroyed
      *
      * @return Lock
      */