diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
index 891bc51bcb..8d167dc92e 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
@@ -2129,6 +2129,11 @@ public function __sleep()
             $serialized[] = 'versionField';
         }
 
+        if ($this->isLockable) {
+            $serialized[] = 'isLockable';
+            $serialized[] = 'lockField';
+        }
+
         if ($this->lifecycleCallbacks) {
             $serialized[] = 'lifecycleCallbacks';
         }