self: super:
{
  python38Packages = super.python3Packages // {
    twisted = with super.python3Packages;
      twisted.overrideAttrs (old: rec {
        version = "21.2.0";
        src = fetchPypi {
          inherit version;
          extension = "tar.gz";
          pname = "Twisted";
          sha256 = "04jsr67swzj8vn8z64fzbha7vpkm1jz9ns26566vjsfg8n4llm3p";
        };
      });
  };

  matrix-synapse = super.matrix-synapse.overrideAttrs (old: {
    propagatedBuildInputs = with self.python3Packages; [
      setuptools
      bcrypt
      bleach
      canonicaljson
      daemonize
      frozendict
      jinja2
      jsonschema
      lxml
      msgpack
      netaddr
      phonenumbers
      pillow
      prometheus_client
      psutil
      psycopg2
      pyasn1
      pymacaroons
      pynacl
      pyopenssl
      pysaml2
      pyyaml
      requests
      signedjson
      sortedcontainers
      treq
      twisted
      unpaddedbase64
      typing-extensions
      authlib
      pyjwt
      systemd
      hiredis
    ];
    python = self.python3;
  });
}