diff --git a/app/controllers/studip_controller.php b/app/controllers/studip_controller.php
index 812ea4a9b7cb7dfa52d5ea3c00d385db8ce33fd4..0e340d6d722485a18f58df482d3c7aadff2cb0f3 100644
--- a/app/controllers/studip_controller.php
+++ b/app/controllers/studip_controller.php
@@ -321,7 +321,9 @@ abstract class StudipController extends Trails_Controller
      */
     public function redirect($to)
     {
-        $to = $this->url_for(...func_get_args());
+        if (func_num_args() > 1) {
+            $to = $this->url_for(...func_get_args());
+        }
         return parent::redirect($to);
     }