diff --git a/vendor/underscore.js b/vendor/underscore.js
index 4f5601325..7f7bd5b50 100644
--- a/vendor/underscore.js
+++ b/vendor/underscore.js
@@ -836,4 +836,5 @@
     return this._wrapped;
   };
 
-})();
+// fix for 'use strict' - need an explicit `this`
+}).call(this || window);