diff --git a/src/environment.js b/src/environment.js
index e3e4d6665..568bfd9eb 100644
--- a/src/environment.js
+++ b/src/environment.js
@@ -1,9 +1,8 @@
 "use strict";
-var extend = require('util')._extend;
 
-extend(exports, require('./environment_browser'));
+Object.assign(exports, require('./environment_browser'));
 
-extend(exports, {
+Object.assign(exports, {
   TransportUDP: require('./TransportUDP'),
   TransportTCP: require('./TransportTCP'),
   WebSocket: require('ws'),