diff --git a/src/ajax.js b/src/ajax.js
index cea2c6c12..95a63fa81 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -184,13 +184,17 @@
 
   $.ajax = function(options){
     var settings = $.extend({}, options || {}),
-        deferred = $.Deferred && $.Deferred()
+        deferred = $.Deferred && $.Deferred(),
+        urlAnchor
     for (key in $.ajaxSettings) if (settings[key] === undefined) settings[key] = $.ajaxSettings[key]
 
     ajaxStart(settings)
 
-    if (!settings.crossDomain) settings.crossDomain = /^([\w-]+:)?\/\/([^\/]+)/.test(settings.url) &&
-      RegExp.$2 != window.location.host
+    if (!settings.crossDomain) {
+      urlAnchor = document.createElement('a')
+      urlAnchor.href = settings.url
+      settings.crossDomain = (window.location.protocol + '//' + window.location.host) !== (urlAnchor.protocol + '//' + urlAnchor.host)
+    }
 
     if (!settings.url) settings.url = window.location.toString()
     serializeData(settings)
diff --git a/test/ajax.html b/test/ajax.html
index 7f0d3df8a..c3afd404b 100644
--- a/test/ajax.html
+++ b/test/ajax.html
@@ -832,7 +832,7 @@ <h1>Zepto Ajax unit tests</h1>
       overrideMimeType: function(type) {
         this.responseHeaders['content-type'] = type
       },
-      withCredentials: false, 
+      withCredentials: false,
       send: function(data) {
         this.data = data
       },
@@ -881,7 +881,7 @@ <h1>Zepto Ajax unit tests</h1>
         t.assertEqual(window.location, MockXHR.last.url)
       },
 
-      testCrossDomain: function(t) {
+      testCrossDomainCrossOrigin: function(t) {
         $.ajax({
           url: 'http://example.com/foo',
           beforeSend: function(xhr, settings) {
@@ -890,6 +890,60 @@ <h1>Zepto Ajax unit tests</h1>
         })
       },
 
+      testCrossDomainSameOrigin: function(t) {
+        $.ajax({
+          url: window.location.href,
+          beforeSend: function(xhr, settings) {
+            t.assertFalse(settings.crossDomain)
+          }
+        })
+      },
+
+      testCrossDomainLeadingSpace: function(t) {
+        $.ajax({
+          url: ' http://example.com/foo',
+          beforeSend: function(xhr, settings) {
+            t.assertTrue(settings.crossDomain)
+          }
+        })
+      },
+
+      testCrossDomainTrippleSlash: function(t) {
+        $.ajax({
+          url: 'http:///example.com/foo',
+          beforeSend: function(xhr, settings) {
+            t.assertTrue(settings.crossDomain)
+          }
+        })
+      },
+
+      testCrossDomainWithQuery: function(t) {
+        $.ajax({
+          url: window.location.href + "?foo=bar",
+          beforeSend: function(xhr, settings) {
+            t.assertFalse(settings.crossDomain)
+          }
+        })
+      },
+
+      testCrossDomainDifferentScheme: function(t) {
+        $.ajax({
+          url: "foo://" + window.location.host,
+          beforeSend: function(xhr, settings) {
+            t.assertTrue(settings.crossDomain)
+          }
+        })
+      },
+
+      testCrossDomainPeriodInScheme: function(t) {
+        $.ajax({
+          url: "foo.bar://example.com/foo",
+          beforeSend: function(xhr, settings) {
+            t.assertTrue(settings.crossDomain)
+          }
+        })
+      },
+
       testDefaultAcceptHeader: function(t) {
         $.ajax()
         t.assert(MockXHR.last.headers.some(matchHeader('Accept', '*/*')))