diff --git a/include/ajax.content.php b/include/ajax.content.php
index acc238c34e828c414d3be133c836bb82d3f311b7..2c0e056b5e5a9ce02584badc417a9480023c2446 100644
--- a/include/ajax.content.php
+++ b/include/ajax.content.php
@@ -103,7 +103,7 @@ class ContentAjaxAPI extends AjaxController {
         return $content;
     }
 
-    function getSignature($type, $id) {
+    function getSignature($type, $id=null) {
         global $thisstaff;
 
         if (!$thisstaff)