diff --git a/src/app/code/community/Zendesk/Zendesk/controllers/ApiController.php b/src/app/code/community/Zendesk/Zendesk/controllers/ApiController.php
index 54dc0e1..5a490a3 100644
--- a/src/app/code/community/Zendesk/Zendesk/controllers/ApiController.php
+++ b/src/app/code/community/Zendesk/Zendesk/controllers/ApiController.php
@@ -247,6 +247,7 @@ public function usersAction()
                 case 'given_name':
                 case 'givenname':
                 case 'first_name':
+                default:
                     $sort = 'firstname';
                     break;