diff --git a/src/octoprint/static/js/app/client/base.js b/src/octoprint/static/js/app/client/base.js
index dccfa67f..5d541ec4 100644
--- a/src/octoprint/static/js/app/client/base.js
+++ b/src/octoprint/static/js/app/client/base.js
@@ -222,7 +222,12 @@
 
         var headers = OctoPrint.getRequestHeaders();
 
-        request.open("POST", OctoPrint.getBaseUrl() + url);
+        var urlToCall = url;
+        if (!_.startsWith(url, "http://") && !_.startsWith(url, "https://")) {
+            urlToCall = OctoPrint.getBaseUrl() + url;
+        }
+
+        request.open("POST", urlToCall);
         _.each(headers, function(value, key) {
             request.setRequestHeader(key, value);
         });