diff --git a/IPython/html/static/notebook/js/widgetmanager.js b/IPython/html/static/notebook/js/widgetmanager.js
index 0e94bda..e2dfe20 100644
--- a/IPython/html/static/notebook/js/widgetmanager.js
+++ b/IPython/html/static/notebook/js/widgetmanager.js
@@ -23,6 +23,7 @@
     // elsewhere.
     define(["underscore",
              "backbone",
+            ], function (Underscore, Backbone) {
 
         //--------------------------------------------------------------------
         // WidgetManager class