diff --git a/overlays/nixpkgs/firefox.nix b/overlays/nixpkgs/firefox.nix
index 5eee596..7ce654b 100644
--- a/overlays/nixpkgs/firefox.nix
+++ b/overlays/nixpkgs/firefox.nix
@@ -2,7 +2,8 @@
 
 { pkgs, ... }: final: prev: {
   firefox-esr = let
-    sandboxed-firefox-esr = pkgs.mkNixPak {
+    cleanPkgs = import pkgs.path {};
+    sandboxed-firefox-esr = cleanPkgs.mkNixPak {
       config = { sloth, ... }: {
         app.package = pkgs.firefox-esr;
         app.binPath = "bin/firefox-esr";