diff --git a/overlays/nixpak/firefox.nix b/overlays/nixpak/firefox.nix
index 2c8d14a..40fc99f 100644
--- a/overlays/nixpak/firefox.nix
+++ b/overlays/nixpak/firefox.nix
@@ -83,6 +83,7 @@
       desktopName = "Firefox ESR";
       icon = "firefox";
       wmClass = "firefox-esr";
+      hasMozSystemDirPatch = true;
     };
   in
     wrappedFirefox;