diff --git a/javascript/jquery-ondemand/jquery.ondemand.js b/javascript/jquery-ondemand/jquery.ondemand.js
index 90f9b18c6..fab4bce2a 100644
--- a/javascript/jquery-ondemand/jquery.ondemand.js
+++ b/javascript/jquery-ondemand/jquery.ondemand.js
@@ -1,11 +1,17 @@
 /**
  * On-demand JavaScript handler
+ * 
  * Based on http://plugins.jquery.com/files/issues/jquery.ondemand.js_.txt 
  * and heavily modified to integrate with SilverStripe and prototype.js.
  * Adds capabilities for custom X-Include-CSS and X-Include-JS HTTP headers
  * to request loading of externals alongside an ajax response.
  * 
- * IMPORTANT: This plugin monkeypatches the jQuery.ajax() method.
+ * Requires jQuery 1.5 ($.Deferred support)
+ * 
+ * CAUTION: Relies on customization of the 'beforeSend' callback in jQuery.ajaxSetup()
+ * 
+ * @author Ingo Schommer (ingo at silverstripe dot com)
+ * @author Sam Minnee (sam at silverstripe dot com)
  */
 (function($){
 
@@ -74,12 +80,12 @@
 		/**
 		 * Process the X-Include-CSS and X-Include-JS headers provided by the Requirements class
 		 */
-		processOnDemandHeaders: function(xml, status, _ondemandComplete) {
-			var self = this;
+		processOnDemandHeaders: function(xml, status, xhr) {
+			var self = this, processDfd = new $.Deferred();
 			
 			// CSS
-			if(xml.getResponseHeader('X-Include-CSS')) {
-				var cssIncludes = xml.getResponseHeader('X-Include-CSS').split(',');
+			if(xhr.getResponseHeader('X-Include-CSS')) {
+				var cssIncludes = xhr.getResponseHeader('X-Include-CSS').split(',');
 				for(var i=0;i<cssIncludes.length;i++) {
 					// Syntax: "URL:##:media"
 					if(cssIncludes[i].match(/^(.*):##:(.*)$/)) {
@@ -93,8 +99,8 @@
 
 			// JavaScript
 			var newJsIncludes = [];
-			if(xml.getResponseHeader('X-Include-JS')) {
-				var jsIncludes = xml.getResponseHeader('X-Include-JS').split(',');
+			if(xhr.getResponseHeader('X-Include-JS')) {
+				var jsIncludes = xhr.getResponseHeader('X-Include-JS').split(',');
 				for(var i=0;i<jsIncludes.length;i++) {
 					if(!$.isItemLoaded(jsIncludes[i])) {
 						newJsIncludes.push(jsIncludes[i]);
@@ -121,7 +127,7 @@
 						async: false
 					});
 				} else {
-					_ondemandComplete(xml, status); 
+					processDfd.resolve(xml, status, xhr);
 				}
 			}
 
@@ -129,44 +135,38 @@
 				getScriptQueue();
 			} else {
 				// If there aren't any new includes, then we can just call the callbacks ourselves                
-				_ondemandComplete(xml, status);
+				processDfd.resolve(xml, status, xhr);
 			}
+			
+			return processDfd.promise();
 		}
-
+		
 	});
 	
-	/**
-	 * Ajax requests are amended to look for X-Include-JS and X-Include-CSS headers
-	 */
-	 _originalAjax = $.ajax;
-	 $.ajax = function(s) {
-		// Avoid recursion in ajax callbacks caused by getScript(), by not parsing
-		// ondemand headers for 'script' datatypes
-		if(s.dataType == 'script') return _originalAjax(s);
-
-		var _complete = s.complete;
-		var _success = s.success;
-		var _dataType = s.dataType;
-
-		// This replaces the usual ajax success & complete handlers.  They are called after any on demand JS is loaded.
-		var _ondemandComplete = function(data, status) {
-			//var status = $.httpSuccess(xml) ? 'success' : 'error';    //rewrote success function as httpSuccess doesn't exist anymore in jQuery 1.5
-			if (typeof status == 'undefined' || status != 'success') status = 'error';
-
-			if(status == 'success') {
-				//var data = jQuery.httpData(xml, _dataType); //unnecessary as data type conversion is automatically done in jQuery 1.5 using the ajaxConvert method
-				if(_success) _success(data, status);
+	$.ajaxSetup({
+		// beforeSend is the only place to access the XHR object before success handlers are added
+		beforeSend: function(jqXHR, s) {
+			// Avoid recursion in ajax callbacks caused by getScript(), by not parsing
+			// ondemand headers for 'script' datatypes
+			if(s.dataType == 'script') return;
+			
+			var dfd = new $.Deferred();
+			
+			// Register our own success handler (assumes no handlers are already registered)
+			// 'success' is an alias for 'done', which is executed by the built-in deferred instance in $.ajax()
+			jqXHR.success(function(success, statusText, jXHR) {
+				$.processOnDemandHeaders(success, statusText, jXHR).done(function() {
+					dfd.resolveWith(s.context || this, [success, statusText, jXHR]);
+				});
+			});
+			
+			// Reroute all external success hanlders through our own deferred.
+			// Not overloading fail() as no event can cause the original request to fail.
+			jqXHR.success = function(callback) {
+				dfd.done(callback);
 			}
-			if(_complete) _complete(data, status);
 		}
-	    
-		// We remove the success handler and take care of calling it outselves within _ondemandComplete
-		s.success = null;
-		s.complete = function(xml, status) {
-			$.processOnDemandHeaders(xml, status, _ondemandComplete);
-		}
-
-		return _originalAjax(s);
-    }
+	});
+	
 
 })(jQuery);
\ No newline at end of file