diff --git a/overlays/nixpak/firefox.nix b/overlays/nixpak/firefox.nix
index ef2c338..2d5df60 100644
--- a/overlays/nixpak/firefox.nix
+++ b/overlays/nixpak/firefox.nix
@@ -59,6 +59,7 @@
             "/etc/resolv.conf"
             "/etc/localtime"
             [ "/etc/firefox" "/app/etc/firefox" ]
+            ["${prev.firefox-esr}/lib/firefox" "/app/etc/firefox-esr"]
             (sloth.concat' sloth.xdgConfigHome "/dconf")
             (sloth.concat' sloth.xdgConfigHome "/gtk-2.0")
             (sloth.concat' sloth.xdgConfigHome "/gtk-3.0")