diff --git a/package.json b/package.json
index 6666d65cd5..08232d3d30 100644
--- a/package.json
+++ b/package.json
@@ -87,7 +87,7 @@
     "stylus-loader": "3.0.1",
     "swagger-jsdoc": "1.9.4",
     "tslint": "5.2.0",
-    "uglify-js": "git+https://github.com/mishoo/UglifyJS2.git#8f4b45f4f814c04918382949b4bcaf7a8d910281",
+    "uglify-js": "git+https://github.com/mishoo/UglifyJS2.git#harmony",
     "webpack": "2.5.1"
   },
   "dependencies": {
diff --git a/webpack/plugins/index.ts b/webpack/plugins/index.ts
index 0692b9f8dd..1f46247eea 100644
--- a/webpack/plugins/index.ts
+++ b/webpack/plugins/index.ts
@@ -1,3 +1,4 @@
+import * as webpack from 'webpack';
 const StringReplacePlugin = require('string-replace-webpack-plugin');
 
 import constant from './const';
@@ -12,7 +13,7 @@ export default () => {
 	];
 
 	if (isProduction) {
-		//plugins.push(new webpack.optimize.UglifyJsPlugin());
+		plugins.push(new webpack.optimize.UglifyJsPlugin());
 	}
 
 	return plugins;