diff --git a/README.md b/README.md
index fe83cdce..d4081e94 100644
--- a/README.md
+++ b/README.md
@@ -171,6 +171,9 @@ Returns the options for the last matched call to fetch
 Set some global config options, which include
 * `sendAsJson` [default `true`] - by default fetchMock will convert objects to JSON before sending. This is overrideable fro each call but for some scenarios e.g. when dealing with a lot of array buffers, it can be useful to default to `false`
 
+##### `setImplementations(opts)`
+When using non global fetch (e.g. a ponyfill) or an alternative Promise implementation, this will configure fetch-mock to use your chosen implementations. `opts` is an object with one or more of the following properties: `Headers`,`Request`,`Response`,`Promise`. Note that `setImplementations(require('fetch-ponyfill'))` will configure fetch-mock to use all of fetch-ponyfill's classes. 
+
 ## Troubleshooting and alternative installation
 
 ### `fetch` is assigned to a local variable, not a global
diff --git a/src/client.js b/src/client.js
index fc495b4a..0a7a8f02 100644
--- a/src/client.js
+++ b/src/client.js
@@ -4,12 +4,14 @@ const FetchMock = require('./fetch-mock');
 const statusTextMap = require('./status-text');
 const theGlobal = typeof window !== 'undefined' ? window : self;
 
-FetchMock.setGlobals({
-	global: theGlobal,
+FetchMock.global = theGlobal;
+FetchMock.statusTextMap = statusTextMap;
+
+FetchMock.setImplementations({
+	Promise: Promise,
 	Request: theGlobal.Request,
 	Response: theGlobal.Response,
-	Headers: theGlobal.Headers,
-	statusTextMap: statusTextMap
+	Headers: theGlobal.Headers
 });
 
 module.exports = new FetchMock()
\ No newline at end of file
diff --git a/src/fetch-mock.js b/src/fetch-mock.js
index b2ced28f..4bc6468a 100644
--- a/src/fetch-mock.js
+++ b/src/fetch-mock.js
@@ -80,7 +80,7 @@ FetchMock.prototype.spy = function () {
 }
 
 FetchMock.prototype.fetchMock = function (url, opts) {
-	const Promise = this.Promise || FetchMock.global.Promise;
+	const Promise = this.Promise || FetchMock.Promise;
 	let response = this.router(url, opts);
 
 	if (!response) {
@@ -130,7 +130,7 @@ FetchMock.prototype.addRoute = function (route) {
 
 
 FetchMock.prototype.mockResponse = function (url, responseConfig, fetchOpts) {
-	const Promise = this.Promise || FetchMock.global.Promise;
+	const Promise = this.Promise || FetchMock.Promise;
 
 	// It seems odd to call this in here even though it's already called within fetchMock
 	// It's to handle the fact that because we want to support making it very easy to add a
@@ -269,8 +269,11 @@ FetchMock.prototype.configure = function (opts) {
 	Object.assign(FetchMock.config, opts);
 }
 
-FetchMock.setGlobals = function (globals) {
-	Object.assign(FetchMock, globals)
+FetchMock.setImplementations = FetchMock.prototype.setImplementations = function (implementations) {
+	FetchMock.Headers = implementations.Headers || FetchMock.Headers;
+	FetchMock.Request = implementations.Request || FetchMock.Request;
+	FetchMock.Response = implementations.Response || FetchMock.Response;
+	FetchMock.Promise = implementations.Promise || FetchMock.Promise;
 }
 
 FetchMock.prototype.sandbox = function (Promise) {
@@ -295,7 +298,9 @@ FetchMock.prototype.sandbox = function (Promise) {
 	functionInstance.bindMethods();
 	boundMock = functionInstance.fetchMock;
 	functionInstance.isSandbox = true;
-	functionInstance.Promise = Promise;
+	if (Promise) {
+		functionInstance.Promise = Promise;
+	}
 
 	return functionInstance;
 };
diff --git a/src/server.js b/src/server.js
index 89c03eb8..0f79d479 100644
--- a/src/server.js
+++ b/src/server.js
@@ -7,13 +7,15 @@ const stream = require('stream');
 const FetchMock = require('./fetch-mock');
 const http = require('http');
 
-FetchMock.setGlobals({
-	global: global,
+FetchMock.global = global;
+FetchMock.statusTextMap = http.STATUS_CODES;
+FetchMock.stream = stream;
+
+FetchMock.setImplementations({
+	Promise: Promise,
 	Request: Request,
 	Response: Response,
-	Headers: Headers,
-	stream: stream,
-	statusTextMap: http.STATUS_CODES
+	Headers: Headers
 });
 
 module.exports = new FetchMock()
\ No newline at end of file
diff --git a/test/spec.js b/test/spec.js
index 6ab8db94..d870ac87 100644
--- a/test/spec.js
+++ b/test/spec.js
@@ -1073,6 +1073,61 @@ module.exports = (fetchMock, theGlobal, Request, Response) => {
 				}
 				fetchMock.restore();
 			});
+
+			describe('fetch utility class implementations', () => {
+				const FetchMock = require('../src/fetch-mock');
+				['Headers', 'Request', 'Response']
+					.forEach(className => {
+						it(`should use configured ${className}`, () => {
+							const original = FetchMock[className];
+							sinon.spy(FetchMock, className);
+							const spy = FetchMock[className];
+							let callCount = 0;
+							const custom = function () {
+								callCount++;
+								return spy.apply(this, arguments)
+							};
+							custom.prototype = original.prototype;
+							const confObject = {};
+							confObject[className] = custom
+							fetchMock.setImplementations(confObject);
+							expect(FetchMock[className]).to.equal(custom);
+
+							fetchMock.mock('http://test.url.com/', {
+								status: 200,
+								headers: {
+									id: 1
+								}
+							});
+							return Promise.all([
+								fetch('http://test.url.com/'),
+								fetch(new FetchMock.Request('http://test.url.com/'))
+							])
+								.then(() => {
+									expect(callCount).to.equal(spy.args.length);
+									confObject[className] = original;
+									fetchMock.restore();
+									fetchMock.setImplementations(confObject);
+								})
+						})
+
+					})
+			});
+
+			it('can be configured to use alternate Promise implementations', () => {
+				fetchMock.setImplementations({
+					Promise: BluebirdPromise
+				});
+				fetchMock
+					.mock('http://example.com', 200)
+				const fetchCall = fetch('http://example.com');
+				expect(fetchCall).to.be.instanceof(BluebirdPromise);
+				return fetchCall.then(() => {
+					fetchMock.restore();
+					fetchMock.setImplementations({Promise});
+				})
+
+			});
 		})
 
 		describe('sandbox', () => {