self: super: {
  cgit = self.callPackage ./cgit { inherit (super) cgit; };

  dino = self.callPackage ./dino { inherit (super) dino; };

  firefoxPackages = self.callPackage ./firefox/packages.nix {
    inherit (super) firefoxPackages;
    llvmPackages = self.llvmPackages_latest;
  };

  mailmanPackages = super.mailmanPackages.extend (self: super: {
    web = self.callPackage mailman/web.nix { inherit (super) web; };
  });

  public-inbox = self.callPackage ./public-inbox {
    inherit (super) public-inbox;
  };

  python3 = self.callPackage ./python { python = super.python3; };

  thunderbird = self.callPackage ./thunderbird {
    inherit (super) thunderbird;
    llvmPackages = self.llvmPackages_8;
  };
  thunderbird-68 = self.callPackage ./thunderbird {
    thunderbird = super.thunderbird-68;
    llvmPackages = self.llvmPackages_latest;
  };

  tmux = self.callPackage ./tmux { inherit (super) tmux; };

  youtube-dl = self.callPackage ./youtube-dl { inherit (super) youtube-dl; };
}