diff --git a/lib/Gitlab/Model/Project.php b/lib/Gitlab/Model/Project.php
index 3b62a9f7c..e22df239b 100644
--- a/lib/Gitlab/Model/Project.php
+++ b/lib/Gitlab/Model/Project.php
@@ -724,7 +724,7 @@ public function mergeRequest($id)
      */
     public function createMergeRequest($source, $target, $title, $assignee = null, $description = null)
     {
-        $data = $this->client->mergeRequests()->create($this->id, $source, $target, $title, $assignee, null, $description);
+        $data = $this->client->mergeRequests()->create($this->id, $source, $target, $title, $assignee, $this->id, $description);
 
         return MergeRequest::fromArray($this->getClient(), $this, $data);
     }