{
  inputs,
  pkgs,
  ...
}:
inputs.nixpkgs.lib.extend (
  final: prev:
  let
    lib = prev;
  in
  {
    ensureZfsMounts =
      dirs:
      pkgs.writeShellApplication {
        name = "zfslistmounted";
        runtimeInputs = with pkgs; [
          zfs
          gnugrep
          gawk
          coreutils
        ];
        text = ''
          #!/bin/sh
          zfs list -o mountpoint,mounted -H | awk '$2 == "yes" {print $1}' | grep -c '${lib.strings.concatStringsSep "\|" dirs}' | grep -Fq ${toString (lib.length dirs)}
        '';
      };

    serviceMountDeps = serviceName: dirs: {
      systemd.services."${serviceName}_mounts" = {
        unitConfig.Wants = "zfs.target";
        serviceConfig = {
          Type = "oneshot";
          RemainAfterExit = true;
          ExecStart = lib.getExe (final.ensureZfsMounts dirs);
        };
      };

      systemd.services.${serviceName} = {
        wants = [ "${serviceName}_mounts.service" ];
      };
    };

    # stolen from: https://stackoverflow.com/a/42398526
    optimizeWithFlags =
      pkg: flags:
      lib.overrideDerivation pkg (
        old:
        let
          newflags = lib.foldl' (acc: x: "${acc} ${x}") "" flags;
          oldflags = if (lib.hasAttr "NIX_CFLAGS_COMPILE" old) then "${old.NIX_CFLAGS_COMPILE}" else "";
        in
        {
          NIX_CFLAGS_COMPILE = "${oldflags} ${newflags}";
          # stdenv = pkgs.clang19Stdenv;
        }
      );

    optimizePackage =
      pkg:
      final.optimizeWithFlags pkg [
        "-O3"
        "-march=znver3"
        "-mtune=znver3"
      ];
  }
)