{
  perSystem = { pkgs, ... }: {
    packages.stop-using-nix-env = let
      site = with pkgs; stdenvNoCC.mkDerivation rec {
        pname = "stop-using-nix-env";
        version = "1.2.1";
        src = ./src;
        buildCommand = ''
          install -Dm644 $src/* -t $out/share/www/${pname}
          substituteInPlace $out/share/www/${pname}/index.html \
            --replace '<!-- VERSION -->' 'Version ${version} |'
        '';
        passthru = {
          webroot = "${site}/share/www/${pname}";
        };
      };
    in site;
  };
}