--- a/mobile/chrome/content/browser-ui.js
+++ b/mobile/chrome/content/browser-ui.js
@@ -2526,17 +2526,18 @@ var BadgeHandlers = {
         // Get the feed and read the count, passing any saved username and password
         // but do not show any security dialogs if we fail
         let req = new XMLHttpRequest();
         req.mozBackgroundRequest = true;
         req.open("GET", "https://mail.google.com/mail/feed/atom", true, login.username, login.password);
         req.onreadystatechange = function(aEvent) {
           if (req.readyState == 4) {
             if (req.status == 200) {
-              this._lastCount = req.responseXML.getElementsByTagName("fullcount")[0].childNodes[0].nodeValue;
+              let count = req.responseXML.getElementsByTagName("fullcount");
+              this._lastCount = count ? count[0].childNodes[0].nodeValue : 0;
             } else {
               this._lastCount = 0;
             }
             this._lastCount = BadgeHandlers.setNumberBadge(aBadge, this._lastCount);
           }
         };
         req.send(null);
       }