diff --git a/chrome/content/zotero/xpcom/file.js b/chrome/content/zotero/xpcom/file.js
index c28217e6e..84d3982c0 100644
--- a/chrome/content/zotero/xpcom/file.js
+++ b/chrome/content/zotero/xpcom/file.js
@@ -332,8 +332,7 @@ 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 6b7591947..c8ee5ee5a 100644
--- a/chrome/content/zotero/xpcom/http.js
+++ b/chrome/content/zotero/xpcom/http.js
@@ -158,8 +158,7 @@ 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;
@@ -367,8 +366,7 @@ 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;
@@ -441,8 +439,7 @@ 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);
@@ -519,8 +516,7 @@ 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);
@@ -567,8 +563,7 @@ 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);
@@ -737,8 +732,7 @@ 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('MKCOL', uri.spec, true);
@@ -769,8 +763,7 @@ 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("DELETE", uri.spec, true);
diff --git a/chrome/content/zotero/xpcom/openurl.js b/chrome/content/zotero/xpcom/openurl.js
index b7b32c3fc..bb0e1116c 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 ed097ace9..95eeb1964 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");
@@ -267,8 +268,7 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 		
 		// Set the locale direction to Zotero.dir
 		// DEBUG: is there a better way to get the entity from JS?
-		var xmlhttp = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
-						.createInstance();
+		var xmlhttp = new XMLHttpRequest();
 		xmlhttp.open('GET', 'chrome://global/locale/global.dtd', false);
 		xmlhttp.overrideMimeType('text/plain');
 		xmlhttp.send(null);