final: prev: let
  lib = prev.lib;
  fonts = ["roboto-mono"];
  ligaturizer = prev.fetchFromGitHub {
    owner = "ToxicFrog";
    repo = "Ligaturizer";
    rev = "v5";
    sha256 = "sha256-sFzoUvA4DB9CVonW/OZWWpwP0R4So6YlAQeqe7HLq50=";
    fetchSubmodules = true;
  };
in
  lib.pipe fonts [
    (builtins.map (name: {
      inherit name;
      value = prev.${name};
    }))
    builtins.listToAttrs
    (builtins.mapAttrs (name: value:
      value.overrideAttrs (
        prevAttrs: {
          outputHash = null;
          outputHashMode = null;
          outputHashAlgo = null;
          nativeBuildInputs = (prevAttrs.nativeBuildInputs or []) ++ [prev.fontforge];
          postFixup =
            (prevAttrs.postFixup or "")
            + ''
              pushd ${ligaturizer}
              mkdir -p $out/share/fonts/truetype
              mkdir -p $out/share/fonts/opentype
              find $out/share/fonts/truetype \
                -name "*.ttf" \
                -exec fontforge \
                -lang py \
                -script ligaturize.py {} \
                --output-dir=$out/share/fonts/truetype \;
              find $out/share/fonts/opentype \
                -name "*.otf" \
                -exec fontforge \
                -lang py \
                -script ligaturize.py {} \
                --output-dir=$out/share/fonts/opentype \;
              popd
            '';
        }
      )))
  ]