diff --git a/mod/chat/gui_header_js/users.php b/mod/chat/gui_header_js/users.php
index 29dc0417984..33555b87d21 100644
--- a/mod/chat/gui_header_js/users.php
+++ b/mod/chat/gui_header_js/users.php
@@ -39,6 +39,7 @@ if (!$cm = get_coursemodule_from_instance('chat', $chatuser->chatid, $courseid))
 }
 
 if ($beep) {
+    $message = new stdClass();
     $message->chatid    = $chatuser->chatid;
     $message->userid    = $chatuser->userid;
     $message->groupid   = $chatuser->groupid;