anchor.diff:    doCheck = (!stdenv.isFreeBSD && !stdenv.isDarwin);
   
     # Fixup broken libtool and pkgconfig files
  -  preFixup = stdenv.lib.optionalString (!stdenv.isDarwin) ''
  +  preFixup = optionalString (!stdenv.isDarwin) ''
       sed -e 's,-ltspi,-L${trousers}/lib -ltspi,' \
           -e 's,-lz,-L${zlib}/lib -lz,' \
           -e 's,-lgmp,-L${gmp}/lib -lgmp,' \
  
positive.code:   enableParallelBuilding = !guileBindings;
  
    buildInputs = [ lzo lzip nettle libtasn1 libidn p11_kit zlib gmp ]
      ++ stdenv.lib.optional stdenv.isLinux trousers
      ++ [ unbound ]
      ++ stdenv.lib.optional guileBindings guile;
  
    nativeBuildInputs = [ perl pkgconfig autoreconfHook ];
  
  
negative.code: 
  assert guileBindings -> guile != null;
  
  let
    inherit (stdenv.lib) optional optionals optionalString;
  in
  stdenv.mkDerivation rec {
    name = "gnutls-${version}";
  
    inherit src patches;
  
    configureFlags =
      # FIXME: perhaps use $SSL_CERT_FILE instead
      optional stdenv.isLinux "--with-default-trust-store-file=/etc/ssl/certs/ca-certificates.crt"
    ++ [
      "--disable-dependency-tracking"
      "--enable-fast-install"
    ] ++ optionals guileBindings
      [ "--enable-guile" "--with-guile-site-dir=\${out}/share/guile/site" ];
  
    # Build of the Guile bindings is not parallel-safe.  See
  