1 files changed, 5 insertions, 1 deletions
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index d45c7c2a..9e9debd8 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -530,7 +530,11 @@ class Popup {
     _getFrameParentElement() {
         const defaultParent = document.body;
         const fullscreenElement = DOM.getFullscreenElement();
-        if (fullscreenElement === null || fullscreenElement.shadowRoot) {
+        if (
+            fullscreenElement === null ||
+            fullscreenElement.shadowRoot ||
+            fullscreenElement.openOrClosedShadowRoot // Available to Firefox 63+ for WebExtensions
+        ) {
             return defaultParent;
         }