diff --git a/taskcluster/docker/firefox-flatpak/org.mozilla.firefox.desktop b/taskcluster/docker/firefox-flatpak/org.mozilla.firefox.desktop
index a9fea7a7024c..80f1e3875fc4 100644
--- a/taskcluster/docker/firefox-flatpak/org.mozilla.firefox.desktop
+++ b/taskcluster/docker/firefox-flatpak/org.mozilla.firefox.desktop
@@ -51,6 +51,8 @@ StartupNotify=true
 Categories=Network;WebBrowser;
 Keywords=web;browser;internet;
 Actions=new-window;new-private-window;profile-manager-window;
+StartupWMClass=Firefox
+
 
 [Desktop Action new-window]
 Name=Open a New Window