diff --git a/IPython/html/static/widgets/js/widget_box.js b/IPython/html/static/widgets/js/widget_box.js
index 60fd4d1..a1e97fe 100644
--- a/IPython/html/static/widgets/js/widget_box.js
+++ b/IPython/html/static/widgets/js/widget_box.js
@@ -58,7 +58,7 @@ define([
             this._flex_changed();
             this._pack_changed();
             this._align_changed();
-            that.update_orientation();
+            this.update_orientation();
         },
 
         update_orientation: function(){