{
  lib,
  sources,
  pkgs,
  ...
}:
let
  inherit (lib.options) mkOption;
  inherit (lib.types) str;
in
{
  imports = [
    # Going full schizo
    "${sources.nixpkgs}/nixos/modules/misc/nixpkgs/read-only.nix"
  ];

  options.nixpkgs.system = mkOption {
    type = str;
    default = pkgs.system;
    readOnly = true;
  };

  config.nixpkgs.pkgs = (
    import sources.nixpkgs {
      hostPlatform = pkgs.stdenv.hostPlatform;
      overlays = [ ];
      config = {
        # Configuration reference:
        # <https://nixos.org/manual/nixpkgs/unstable/#chap-packageconfig>
        # Disallow broken packages to be built.
        allowBroken = false;

        allowUnsupportedSystem = true;

        # Warn when config contains an unrecognized attribute.
        # This might be useful for getting a better configuration.
        warnUndeclaredOptions = true;

        # Allow unfree packages
        allowUnfree = true;

        # Permitted insecure packages in a system.
        # Default to none, add more as necessary.
        # Matrix also likes using deprecated libraries, which tend to go into this list.
        # permittedInsecurePackages = [];

        # Whether to set enableParallelBuilding to true by default while
        # building nixpkgs packages. Changing the default causes a mass rebuild.
        enableParallelBuildingByDefault = false;

        # Whether to expose old attribute names for compatibility.
        # This improves backwards compatibility,
        # which I could not care less about in my configuration.
        allowAliases = false;

        # List of derivation warnings to display while rebuilding.
        #  See: <https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/check-meta.nix>
        showDerivationWarnings = [ ];
      };
    }
  );
}