diff --git a/phantomxhr.js b/phantomxhr.js
index <HASH>..<HASH> 100644
--- a/phantomxhr.js
+++ b/phantomxhr.js
@@ -120,6 +120,12 @@ function setup(){
 				init: function () {

 					var _xhr = window.sinon.useFakeXMLHttpRequest();

 

+					// overrideMimeType is not mocked see this issue

+					// https://github.com/cjohansen/Sinon.JS/issues/559

+					window.sinon.FakeXMLHttpRequest.prototype.overrideMimeType = function() {return;}

+					

+					// we backup _xhr object

+					window.backup_xhr = _xhr;

 					_xhr.upload = document.createElement('div');

 

 					_xhr.onCreate = function (request) {

@@ -362,6 +368,12 @@ function fake(options) {
 			}

 		},

 

+		restore: function(){

+			page.evaluate(function(){

+				window.backup_xhr.restore();

+			});

+		},

+

 		nthRespond: function(nth, response){

 			// if you don't want to respond immediately
fix overrideMimeType function as propose by <URL>