diff --git a/src/d8.js b/src/d8.js
index 27a0bc3..e49c6b7 100644
--- a/src/d8.js
+++ b/src/d8.js
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+(function() {
 "use strict";
 
 // A more universal stringify that supports more types than JSON.
@@ -89,3 +90,6 @@
   }
   return '[' + proxy_type + ' Proxy ' + Stringify(info_object, depth-1) + ']';
 }
+
+return Stringify;
+})();