{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs?rev=20fc948445a6c22d4e8d5178e9a6bc6e1f5417c8";
  };

  outputs = { self, nixpkgs }: {
    nixosConfigurations.catacomb = nixpkgs.lib.nixosSystem {
      system = "aarch64-linux";
      modules = [ ./machine/catacomb ];
    };
    nixosConfigurations.empyrean = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [ ./machine/empyrean ];
    };
  };
}