diff --git a/js/ui/calendar.js b/js/ui/calendar.js
index 241a91db4..432986391 100644
--- a/js/ui/calendar.js
+++ b/js/ui/calendar.js
@@ -773,9 +773,11 @@ var NotificationMessage = new Lang.Class({
 
         this.connect('close', () => {
             this._closed = true;
-            this.notification.destroy(MessageTray.NotificationDestroyedReason.DISMISSED);
+            if (this.notification)
+                this.notification.destroy(MessageTray.NotificationDestroyedReason.DISMISSED);
         });
         this._destroyId = notification.connect('destroy', () => {
+            this.notification = null;
             if (!this._closed)
                 this.close();
         });