{nixpkgs, ...}: {
  # This one brings our custom packages from the 'pkgs' directory
  additions = final: _prev:
    import ../packages {
      pkgs = nixpkgs.legacyPackages.${final.system};
    };

  # This one contains whatever you want to overlay
  # You can change versions, add patches, set compilation flags, anything really.
  # https://nixos.wiki/wiki/Overlays
  modifications = final: prev: {
    # final.fprintd = prev.fprintd.overrideAttrs {
    #   # Source: https://github.com/NixOS/nixpkgs/commit/87ca2dc071581aea0e691c730d6844f1beb07c9f
    #   mesonCheckFlags = [
    #     # PAM related checks are timing out
    #     "--no-suite"
    #     "fprintd:TestPamFprintd"
    #   ];
    # };
  };

  # When applied, the unstable nixpkgs set (declared in the flake inputs) will
  # be accessible through 'pkgs.unstable'
  unstable-packages = final: _prev: {
    unstable = import nixpkgs {
      system = final.system;
      config.allowUnfree = true;
    };
  };
}