diff --git a/.babelrc b/.babelrc
index 140b318..39c1fd6 100644
--- a/.babelrc
+++ b/.babelrc
@@ -1,17 +1,3 @@
 {
-  "presets": [
-    "es2015"
-  ],
-  "plugins": [
-    "add-module-exports",
-    [
-      "babel-plugin-transform-builtin-extend",
-      {
-        "globals": [
-          "Error"
-        ],
-        "approximate": true
-      }
-    ]
-  ]
+  "presets": "./babel-config.js"
 }
diff --git a/babel-config.js b/babel-config.js
new file mode 100644
index 0000000..4281c01
--- /dev/null
+++ b/babel-config.js
@@ -0,0 +1,29 @@
+'use strict';
+
+var plugins = [
+  [
+    "babel-plugin-transform-builtin-extend",
+    {
+      "globals": ["Error"],
+      "approximate": true
+    }
+  ]
+];
+
+var env = process.env.BABEL_ENV || process.env.NODE_ENV;
+
+var modules;
+
+if (env === 'es') {
+  modules = false;
+} else {
+  modules = 'commonjs';
+  plugins.push('add-module-exports');
+}
+
+module.exports = {
+  "presets": [
+    ["es2015", { modules: modules }]
+  ],
+  "plugins": plugins
+};
diff --git a/build.js b/build.js
deleted file mode 100644
index a74c7c7..0000000
--- a/build.js
+++ /dev/null
@@ -1,33 +0,0 @@
-'use strict';
-
-var babel = require('babel-core'),
-  fs = require('fs');
-
-// es5 build
-babel.transformFile('./src/index.js', function(err, result) {
-  if (err) throw err;
-
-  var filename = './lib/index.js';
-  fs.writeFile(filename, result.code, onWriteCompleted(filename));
-});
-
-// jsnext build
-
-var jsnextOpts = {
-  presets: [ [ 'es2015', { modules: false } ] ],
-  babelrc: false
-};
-
-babel.transformFile('./src/index.js', jsnextOpts, function(err, result) {
-  if (err) throw err;
-
-  var filename = './lib/index.jsnext.js';
-  fs.writeFile(filename, result.code, onWriteCompleted(filename));
-});
-
-function onWriteCompleted(filename) {
-  return function(err) {
-    if (err) throw err;
-    console.log(filename + ' written');
-  }
-}
diff --git a/lib/index.js b/lib/index.js
index 3184e58..617bef7 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -76,4 +76,4 @@ var ExtendableError = function (_extendableBuiltin2) {
 }(_extendableBuiltin(Error));
 
 exports.default = ExtendableError;
-module.exports = exports['default'];
\ No newline at end of file
+module.exports = exports['default'];
diff --git a/lib/index.jsnext.js b/lib/index.jsnext.js
index 18765e6..70fbfbc 100644
--- a/lib/index.jsnext.js
+++ b/lib/index.jsnext.js
@@ -4,8 +4,31 @@ function _possibleConstructorReturn(self, call) { if (!self) { throw new Referen
 
 function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
 
-var ExtendableError = function (_Error) {
-  _inherits(ExtendableError, _Error);
+function _extendableBuiltin(cls) {
+  function ExtendableBuiltin() {
+    cls.apply(this, arguments);
+  }
+
+  ExtendableBuiltin.prototype = Object.create(cls.prototype, {
+    constructor: {
+      value: cls,
+      enumerable: false,
+      writable: true,
+      configurable: true
+    }
+  });
+
+  if (Object.setPrototypeOf) {
+    Object.setPrototypeOf(ExtendableBuiltin, cls);
+  } else {
+    ExtendableBuiltin.__proto__ = cls;
+  }
+
+  return ExtendableBuiltin;
+}
+
+var ExtendableError = function (_extendableBuiltin2) {
+  _inherits(ExtendableError, _extendableBuiltin2);
 
   function ExtendableError() {
     var message = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : '';
@@ -44,6 +67,6 @@ var ExtendableError = function (_Error) {
   }
 
   return ExtendableError;
-}(Error);
+}(_extendableBuiltin(Error));
 
-export default ExtendableError;
\ No newline at end of file
+export default ExtendableError;
diff --git a/package.json b/package.json
index da942c4..eefeff6 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,9 @@
   "typings": "./lib/index.d.ts",
   "scripts": {
     "test": "mocha --compilers js:babel-core/register --recursive",
-    "build": "node build.js",
+    "build": "npm run build:commonjs && npm run build:es",
+    "build:commonjs": "cross-env BABEL_ENV=commonjs babel src/index.js --out-file lib/index.js",
+    "build:es": "cross-env BABEL_ENV=es babel src/index.js --out-file lib/index.jsnext.js",
     "prepublish": "npm run build && npm run test"
   },
   "repository": {
@@ -32,6 +34,7 @@
     "babel-plugin-transform-builtin-extend": "^1.1.0",
     "babel-preset-es2015": "^6.6.0",
     "chai": "^3.2.0",
+    "cross-env": "^3.1.3",
     "mocha": "^2.4.5"
   },
   "dependencies": {}