{
  inputs = {
    nixpkgs-firefox = { url = "github:nixos/nixpkgs?ref=34afc31c49b067879c3c49b29c67e2a1bc806685"; flake = false; };
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
  };

  outputs =
    {
      self,
      nixpkgs,
      nixpkgs-firefox,
    }:
    let
      forAllSystems =
        f: nixpkgs.lib.genAttrs [ "x86_64-linux"] (sys: let pkgs = import nixpkgs {system = "x86_64-linux"; overlays = [self.overlays.default];}; in f pkgs);
      overlayBaseInstance = import ./overlay.nix nixpkgs.outPath;
      myOverlay =
        pkgs:
        overlayBaseInstance {
          inherit pkgs;
          oldPkgs = import nixpkgs-firefox {system = "x86_64-linux";};
        };
    in
    {
      overlays.default = final: _: myOverlay final;

      legacyPackages = forAllSystems (pkgs: myOverlay pkgs);
    };
}