diff --git a/ext/fg/js/frontend-initialize.js b/ext/fg/js/frontend-initialize.js
index 2e63c29f..2df59e20 100644
--- a/ext/fg/js/frontend-initialize.js
+++ b/ext/fg/js/frontend-initialize.js
@@ -16,6 +16,7 @@
  */
 
 /* global
+ * DOM
  * FrameOffsetForwarder
  * Frontend
  * PopupProxy
@@ -95,7 +96,7 @@ async function main() {
         }
 
         let popup;
-        if (isIframe && options.general.showIframePopupsInRootFrame && !document.fullscreen && iframePopupsInRootFrameAvailable) {
+        if (isIframe && options.general.showIframePopupsInRootFrame && DOM.getFullscreenElement() === null && iframePopupsInRootFrameAvailable) {
             popup = popups.iframe || await createIframePopupProxy(url, frameOffsetForwarder, disableIframePopupsInRootFrame);
             popups.iframe = popup;
         } else if (proxy) {
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 99610e17..ae158263 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -16,6 +16,7 @@
  */
 
 /* global
+ * DOM
  * apiGetMessageToken
  * apiInjectStylesheet
  */
@@ -271,7 +272,7 @@ class Popup {
     }
 
     _onFullscreenChanged() {
-        const parent = (Popup._getFullscreenElement() || document.body || null);
+        const parent = (DOM.getFullscreenElement() || document.body || null);
         if (parent !== null && this._container.parentNode !== parent) {
             parent.appendChild(this._container);
         }
@@ -365,16 +366,6 @@ class Popup {
         contentWindow.postMessage({action, params, token}, this._targetOrigin);
     }
 
-    static _getFullscreenElement() {
-        return (
-            document.fullscreenElement ||
-            document.msFullscreenElement ||
-            document.mozFullScreenElement ||
-            document.webkitFullscreenElement ||
-            null
-        );
-    }
-
     static _getPositionForHorizontalText(elementRect, width, height, viewport, offsetScale, optionsGeneral) {
         const preferBelow = (optionsGeneral.popupHorizontalTextPosition === 'below');
         const horizontalOffset = optionsGeneral.popupHorizontalOffset * offsetScale;
diff --git a/ext/mixed/js/dom.js b/ext/mixed/js/dom.js
index 03acbb80..31ba33d6 100644
--- a/ext/mixed/js/dom.js
+++ b/ext/mixed/js/dom.js
@@ -62,4 +62,14 @@ class DOM {
             default: return false;
         }
     }
+
+    static getFullscreenElement() {
+        return (
+            document.fullscreenElement ||
+            document.msFullscreenElement ||
+            document.mozFullScreenElement ||
+            document.webkitFullscreenElement ||
+            null
+        );
+    }
 }