diff --git a/lib/install/template.rb b/lib/install/template.rb
index 7029531b0..20b8a1003 100644
--- a/lib/install/template.rb
+++ b/lib/install/template.rb
@@ -30,7 +30,7 @@
 
 puts "Installing all JavaScript dependencies"
 run "#{RbConfig.ruby} ./bin/yarn add webpack webpack-merge js-yaml path-complete-extname " \
-"webpack-manifest-plugin babel-loader@7.x coffee-loader coffee-script " \
+"webpack-manifest-plugin babel-loader@7.x git://github.com/mishoo/UglifyJS2#harmony coffee-loader coffee-script " \
 "babel-core babel-preset-env compression-webpack-plugin rails-erb-loader glob " \
 "extract-text-webpack-plugin node-sass file-loader sass-loader css-loader style-loader " \
 "postcss-loader autoprefixer postcss-smart-import precss"