diff --git a/js/panel_controller.js b/js/panel_controller.js
index 0c8e62dc8..ef1f9e8fe 100644
--- a/js/panel_controller.js
+++ b/js/panel_controller.js
@@ -114,7 +114,7 @@
 
     /* Inbox window controller */
     var inboxOpened = false;
-    var inboxWindowId = 0;
+    var inboxWindowId = 'inbox';
     window.openInbox = function() {
         if (inboxOpened === false) {
             inboxOpened = true;