diff --git a/chrome/content/zotero/xpcom/file.js b/chrome/content/zotero/xpcom/file.js
index 72c6647c82..af7feb4813 100644
--- a/chrome/content/zotero/xpcom/file.js
+++ b/chrome/content/zotero/xpcom/file.js
@@ -333,8 +333,7 @@ Zotero.File = new function(){
 	 * Runs synchronously, so should only be run on local (e.g. chrome) URLs
 	 */
 	function getContentsFromURL(url) {
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-						.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		xmlhttp.open('GET', url, false);
 		xmlhttp.overrideMimeType("text/plain");
 		xmlhttp.send(null);
diff --git a/chrome/content/zotero/xpcom/http.js b/chrome/content/zotero/xpcom/http.js
index 56baa55ced..3404621264 100644
--- a/chrome/content/zotero/xpcom/http.js
+++ b/chrome/content/zotero/xpcom/http.js
@@ -175,8 +175,7 @@ Zotero.HTTP = new function() {
 		var deferred = Zotero.Promise.defer();
 		
 		if (!this.mock) {
-			var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-				.createInstance();
+			var xmlhttp = new XMLHttpRequest();
 		}
 		else {
 			var xmlhttp = new this.mock;
@@ -456,8 +455,7 @@ Zotero.HTTP = new function() {
 			return false;
 		}
 		
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-						.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		
 		// Prevent certificate/authentication dialogs from popping up
 		xmlhttp.mozBackgroundRequest = true;
@@ -530,8 +528,7 @@ Zotero.HTTP = new function() {
 			return false;
 		}
 		
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-					.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		// Prevent certificate/authentication dialogs from popping up
 		xmlhttp.mozBackgroundRequest = true;
 		xmlhttp.open('POST', url, true);
@@ -608,8 +605,7 @@ Zotero.HTTP = new function() {
 		
 		// Workaround for "Accept third-party cookies" being off in Firefox 3.0.1
 		// https://www.zotero.org/trac/ticket/1070
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-						.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		// Prevent certificate/authentication dialogs from popping up
 		xmlhttp.mozBackgroundRequest = true;
 		xmlhttp.open('HEAD', url, true);
@@ -656,8 +652,7 @@ Zotero.HTTP = new function() {
 			return false;
 		}
 		
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-					.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		// Prevent certificate/authentication dialogs from popping up
 		xmlhttp.mozBackgroundRequest = true;
 		xmlhttp.open('OPTIONS', uri.spec, true);
diff --git a/chrome/content/zotero/xpcom/openurl.js b/chrome/content/zotero/xpcom/openurl.js
index a96175ebba..9e6ad0bf78 100644
--- a/chrome/content/zotero/xpcom/openurl.js
+++ b/chrome/content/zotero/xpcom/openurl.js
@@ -47,7 +47,7 @@ Zotero.OpenURL = new function() {
 	 * Queries OCLC's OpenURL resolver registry and returns an address and version
 	 */
 	function discoverResolvers() {
-		var req = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance();
+		var req = new XMLHttpRequest();
 		req.open("GET", "http://worldcatlibraries.org/registry/lookup?IP=requestor", false);
 		req.send(null);
 		
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index bcbda180f2..c8d2c20b7a 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -24,6 +24,7 @@
 */
 
 // Commonly used imports accessible anywhere
+Components.utils.importGlobalProperties(["XMLHttpRequest"]);
 Components.utils.import("resource://zotero/config.js");
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 Components.utils.import("resource://gre/modules/Services.jsm");
@@ -239,7 +240,7 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 		Zotero.browser = "g";
 		
 		Zotero.Intl.init();
-
+		
 		Zotero.Prefs.init();
 		Zotero.Debug.init(options && options.forceDebugLog);