diff --git a/js/h5p.js b/js/h5p.js
index aee90e2..dd74a79 100644
--- a/js/h5p.js
+++ b/js/h5p.js
@@ -247,7 +247,7 @@ H5P.init = function (target) {
       if (H5P.externalEmbed === false) {
         // Internal embed
         // Make it possible to resize the iframe when the content changes size. This way we get no scrollbars.
-        var iframe = window.parent.document.getElementById('h5p-iframe-' + contentId);
+        var iframe = window.frameElement;
         var resizeIframe = function () {
           if (window.parent.H5P.isFullscreen) {
             return; // Skip if full screen.