anchor.diff:  let
     name = "wireguard-${version}";
   
  -  version = "0.0.20171111";
  +  version = "0.0.20171221";
   
     src = fetchurl {
       url    = "https://git.zx2c4.com/WireGuard/snapshot/WireGuard-${version}.tar.xz";
  -    sha256 = "0mqix3v4qqwwa7hcd0h5rcwhc7yvm9jcl8b3v1vc4sj0m637fd6r";
  +    sha256 = "1vf5dbwc2lgcf28k1m919w94hil2gcl0l4h4da1sh6r7kdz6k5rb";
     };
   
     meta = with stdenv.lib; {
  
positive.code: { stdenv, fetchurl, libmnl, kernel ? null }:
  
  # module requires Linux >= 3.10 https://www.wireguard.io/install/#kernel-requirements
  assert kernel != null -> stdenv.lib.versionAtLeast kernel.version "3.10";
  
negative.code:     INSTALL_MOD_PATH = "\${out}";
  
      NIX_CFLAGS = ["-Wno-error=cpp"];
  
      buildInputs = [ libelf ];
  
      buildPhase = "make module";
    };
  