diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index a607b2c7fdb..7249f4d9019 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -274,7 +274,10 @@ class assign {
     public function get_return_params() {
         global $PAGE;
 
-        $params = $PAGE->url->params();
+        $params = array();
+        if (!WS_SERVER) {
+            $params = $PAGE->url->params();
+        }
         unset($params['id']);
         unset($params['action']);
         return $params;