--- a/mobile/components/BrowserStartup.js
+++ b/mobile/components/BrowserStartup.js
@@ -88,17 +88,17 @@ BrowserStartup.prototype = {
           let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
                           createInstance(Ci.nsIScriptableUnicodeConverter);
           let jsonStr = "";
           try {
             converter.charset = "UTF-8";
             jsonStr = converter.convertFromByteArray(aResult, aResult.length);
 
             PlacesUtils.restoreBookmarksFromJSONString(jsonStr, true);
-          } catch (ex) {
+          } catch (err) {
             Cu.reportError("Failed to parse default bookmarks from bookmarks.json: " + err);
           }
         }
       };
 
       let ioSvc = Cc["@mozilla.org/network/io-service;1"].
                   getService(Ci.nsIIOService);
       let uri = ioSvc.newURI("chrome://browser/locale/bookmarks.json", null, null);