diff --git a/package.json b/package.json
index d6569f86..79a9d572 100644
--- a/package.json
+++ b/package.json
@@ -88,6 +88,7 @@
     "eslint-plugin-react": "^6.2.0",
     "font-awesome": "^4.6.3",
     "glob": "^7.0.6",
+    "google-closure-compiler-js": "^20160828.0.1",
     "gulp": "^3.9.1",
     "jsdom": "^9.4.5",
     "mocha": "^3.0.2",
diff --git a/webpack.config.js b/webpack.config.js
index 6abaec77..bff60449 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -4,6 +4,8 @@
 
 const assert = require('assert');
 
+const ClosureCompiler = require('google-closure-compiler-js').webpack;
+
 const isRelease = process.env.NODE_ENV === 'production';
 
 const KAREN_ENTRY_POINT = process.env.KAREN_ENTRY_POINT;
@@ -59,6 +61,24 @@ else {
     ]);
 }
 
+const webpackPlugins = [];
+if (isRelease) {
+    // https://github.com/google/closure-compiler-js
+    const closure = new ClosureCompiler({
+        options: {
+            languageIn: 'ECMASCRIPT6',
+            languageOut: 'ECMASCRIPT5_STRICT',
+            compilationLevel: 'SIMPLE',
+            warningLevel: 'VERBOSE',
+
+            createSourceMap: true,
+            rewritePolyfills: false,
+            useTypesForOptimization: false,
+        },
+    });
+    webpackPlugins.push(closure);
+}
+
 module.exports = {
     bail: true,
 
@@ -98,4 +118,6 @@ module.exports = {
             }
         ]
     },
+
+    plugins: webpackPlugins,
 };