{
  lib,
  ...
}: {

  # ...
  nix.settings = {
    # allow substituters to be used

    substituters = [
        # also add mirrors?
        #   "https://mirrors.ustc.edu.cn/nix-channels/store"
        "https://cache.nixos.org"
    ];

    trusted-public-keys = [
      # the default public key of cache.nixos.org, it's built-in, no need to add it here
      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
    ];
  };

}