{
  description = "Syndicate utilities";

  outputs = { self, nixpkgs }: {
    lib = nixpkgs.lib.extend (import ./lib.nix);

    overlays.default = import ./overlay.nix;

    legacyPackages =
      self.lib.mapAttrs (system: pkgs: pkgs.extend self.overlays.default) {
        inherit (nixpkgs.legacyPackages) x86_64-linux;
      };

    packages = self.lib.mapAttrs (system: pkgs:
      with pkgs; {
        inherit fontconfig_actor libnotify_actor noise-c preserves-tools squeak
          squeaker syndicate-server syndicated-open syndicate_utils;
        preserves-py = python3Packages.preserves;
        syndicate-py = python3Packages.syndicate-py;
      }) self.legacyPackages;

    nixosModules.default = self.nixosModules.syndicate-server;
    nixosModules.syndicate-server =
      # A little hack to apply our overlay to this module only.
      { config, lib, pkgs, ... }:
      (import ./nixos/syndicate-server.nix) {
        inherit config lib;
        pkgs = pkgs.extend self.overlays.default;
      };

    devShells = self.lib.mapAttrs (system: pkgs:
      with pkgs; {
        default =
          mkShell { packages = builtins.attrValues self.packages.${system}; };
      }) self.legacyPackages;

    checks = self.lib.mapAttrs (system: pkgs':
      with import (nixpkgs + "/nixos/lib/testing-python.nix") {
        inherit system;
        pkgs = pkgs';
      }; {
        simple = simpleTest {
          name = "http";
          nodes.machine = { config, pkgs, ... }: {
            imports = [ self.nixosModules.syndicate-server ];

            nixpkgs.pkgs = pkgs';

            services.syndicate.tty1 = {
              enable = true;
              user = "loser";
              config = [ ];
            };
            users.users.loser.isNormalUser = true;
          };
          testScript = ''
            machine.wait_for_job("syndicate-tty1")
          '';
        };
      }) { inherit (self.legacyPackages) x86_64-linux; };
  };
}