{
  nix = {
    extraOptions = "gc-keep-outputs = true";
    settings = {
      experimental-features = ["nix-command" "flakes"];

      substituters = [
        "https://nix-community.cachix.org"
        "https://callumio-public.cachix.org"
      ];

      trusted-public-keys = [
        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
        "callumio-public.cachix.org-1:VucOSl7vh44GdqcILwMIeHlI0ufuAnHAl8cO1U/7yhg="
      ];
    };
  };
}