diff --git a/src/openseadragon.js b/src/openseadragon.js
index 3be339af..8b8c6a14 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -1725,6 +1725,21 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
             return value ? value : null;
         },
 
+        /**
+         * Retrieves the protocol used by the url. The url can either be absolute
+         * or relative.
+         * @function
+         * @param {String} url The url to retrieve the protocol from.
+         * @return {String} The protocol (http:, https:, file:, ftp: ...)
+         */
+        getUrlProtocol: function( url ) {
+            var match = url.match(/^([a-z]+:)\/\//i);
+            if ( match === null ) {
+                // Relative URL, retrive the protocol from window.location
+                return window.location.protocol;
+            }
+            return match[1].toLowerCase();
+        },
 
         createAjaxRequest: function(){
             var request;
@@ -1778,10 +1793,13 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
                 if ( request.readyState == 4 ) {
                     request.onreadystatechange = function(){};
 
-                    if ( request.status == 200 ) {
+                    var protocol = $.getUrlProtocol( url );
+                    var successStatus =
+                        protocol === "http:" || protocol === "https:" ? 200 : 0;
+                    if ( request.status === successStatus ) {
                         onSuccess( request );
                     } else {
-                        $.console.log( "AJAX request returned %s: %s", request.status, url );
+                        $.console.log( "AJAX request returned %d: %s", request.status, url );
 
                         if ( $.isFunction( onError ) ) {
                             onError( request );
diff --git a/test/basic.js b/test/basic.js
index 946a8ff3..969f492f 100644
--- a/test/basic.js
+++ b/test/basic.js
@@ -56,7 +56,7 @@
 
             equal($(".openseadragon-message").length, 1, "Open failures should display a message");
 
-            ok(testLog.log.contains('["AJAX request returned %s: %s",404,"/test/data/not-a-real-file"]'),
+            ok(testLog.log.contains('["AJAX request returned %d: %s",404,"/test/data/not-a-real-file"]'),
                "AJAX failures should be logged to the console");
 
             start();
diff --git a/test/utils.js b/test/utils.js
index f46f9a84..92538375 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -87,6 +87,30 @@
         );
     });
 
+    test("getUrlProtocol", function() {
+
+        equal(OpenSeadragon.getUrlProtocol("test"), window.location.protocol,
+            "'test' url protocol should be window.location.protocol");
+
+        equal(OpenSeadragon.getUrlProtocol("/test"), window.location.protocol,
+            "'/test' url protocol should be window.location.protocol");
+
+        equal(OpenSeadragon.getUrlProtocol("//test"), window.location.protocol,
+            "'//test' url protocol should be window.location.protocol");
+
+        equal(OpenSeadragon.getUrlProtocol("http://test"), "http:",
+            "'http://test' url protocol should be http:");
+
+        equal(OpenSeadragon.getUrlProtocol("https://test"), "https:",
+            "'https://test' url protocol should be https:");
+
+        equal(OpenSeadragon.getUrlProtocol("file://test"), "file:",
+            "'file://test' url protocol should be file:");
+
+        equal(OpenSeadragon.getUrlProtocol("FTP://test"), "ftp:",
+            "'FTP://test' url protocol should be ftp:");
+    });
+
     // ----------
     asyncTest("requestAnimationFrame", function() {
         var timeWatcher = Util.timeWatcher();