diff --git a/javascripts/tagmanagerHelper.js b/javascripts/tagmanagerHelper.js
index 632f1300f..81c4faef7 100644
--- a/javascripts/tagmanagerHelper.js
+++ b/javascripts/tagmanagerHelper.js
@@ -266,7 +266,7 @@
         ajaxRequest.send();
     };
     tagManagerHelper.updateDebugSiteFlag = function (url, idContainer, debugFlag) {
-        if (!url || !idContainer || !debugFlag) {
+        if (!url || !idContainer || !debugFlag || !(/^https?:\/\//.test(url))) {
             return;
         }
         window.open(url + (url.indexOf('?') == -1 ? '?' : '&') + 'mtmPreviewMode=' + encodeURIComponent(idContainer) + '&mtmSetDebugFlag=' + encodeURIComponent(debugFlag), '_blank', 'noreferrer');