diff --git a/lib/group/backend.php b/lib/group/backend.php
index d0bc970da7..af6c53c803 100644
--- a/lib/group/backend.php
+++ b/lib/group/backend.php
@@ -89,7 +89,7 @@ abstract class OC_Group_Backend {
 	 * @return bool
 	 */
 	public function groupExists($gid){
-		if(!$backend->implementsActions(OC_GROUP_BACKEND_GET_GROUPS)){
+		if(!$this->implementsActions(OC_GROUP_BACKEND_GET_GROUPS)){
 			return false;
 		}
 		return in_array($gid, $this->getGroups());