diff --git a/fetch.js b/fetch.js
index f2f466d7..98b1f2be 100644
--- a/fetch.js
+++ b/fetch.js
@@ -1,14 +1,20 @@
-(function(self) {
+(function(root, factory) {
+  /* jshint strict:false */
+  /* globals define, module */
+  if (typeof define === 'function' && define.amd) {
+    define([], function() { return factory({}, root) })
+  } else if (typeof module === 'object' && module.exports) {
+    factory(module.exports, root)
+  } else {
+    root.WHATWGFetch = factory({}, root)
+  }
+})(typeof self !== 'undefined' ? self : this, function(exports, global) {
   'use strict';
 
-  if (self.fetch) {
-    return
-  }
-
   var support = {
-    searchParams: 'URLSearchParams' in self,
-    iterable: 'Symbol' in self && 'iterator' in Symbol,
-    blob: 'FileReader' in self && 'Blob' in self && (function() {
+    searchParams: 'URLSearchParams' in global,
+    iterable: 'Symbol' in global && 'iterator' in Symbol,
+    blob: 'FileReader' in global && 'Blob' in global && (function() {
       try {
         new Blob()
         return true
@@ -16,8 +22,8 @@
         return false
       }
     })(),
-    formData: 'FormData' in self,
-    arrayBuffer: 'ArrayBuffer' in self
+    formData: 'FormData' in global,
+    arrayBuffer: 'ArrayBuffer' in global
   }
 
   if (support.arrayBuffer) {
@@ -415,11 +421,11 @@
     return new Response(null, {status: status, headers: {location: url}})
   }
 
-  self.Headers = Headers
-  self.Request = Request
-  self.Response = Response
+  exports.Headers = Headers
+  exports.Request = Request
+  exports.Response = Response
 
-  self.fetch = function(input, init) {
+  exports.fetch = function(input, init) {
     return new Promise(function(resolve, reject) {
       var request = new Request(input, init)
       var xhr = new XMLHttpRequest()
@@ -462,5 +468,14 @@
       xhr.send(typeof request._bodyInit === 'undefined' ? null : request._bodyInit)
     })
   }
-  self.fetch.polyfill = true
-})(typeof self !== 'undefined' ? self : this);
+  exports.fetch.polyfill = true
+
+  if (!global.fetch) {
+    global.fetch = exports.fetch
+    global.Headers = Headers
+    global.Request = Request
+    global.Response = Response
+  }
+
+  return exports
+});
diff --git a/script/test b/script/test
index bc471d43..0fd46821 100755
--- a/script/test
+++ b/script/test
@@ -7,3 +7,5 @@ if [ -n "$SAUCE_BROWSER" ]; then
 else
   ./script/phantomjs
 fi
+
+./node_modules/mocha/bin/mocha test/cjs.js
diff --git a/test/cjs.js b/test/cjs.js
new file mode 100644
index 00000000..4d53cf34
--- /dev/null
+++ b/test/cjs.js
@@ -0,0 +1,13 @@
+/* global describe, it, require */
+
+var isFunction = require('chai').assert.isFunction
+var WHATWGFetch = require('../')
+
+describe('Common JS exports', function() {
+  it('should provide all the CJS exports', function() {
+    isFunction(WHATWGFetch.fetch)
+    isFunction(WHATWGFetch.Headers)
+    isFunction(WHATWGFetch.Request)
+    isFunction(WHATWGFetch.Response)
+  })
+})