anchor.diff:  in
   stdenv.mkDerivation rec {
     pname   = "mimalloc";
  -  version = "2.0.2";
  +  version = "2.0.5";
   
     src = fetchFromGitHub {
       owner  = "microsoft";
       repo   = pname;
       rev    = "v${version}";
  -    sha256 = "sha256-n4FGld3bq6ZOSLTzXcVlucCGbQ5/eSFbijU0dfBD/T0=";
  +    sha256 = "sha256-q3W/w1Ofqt6EbKF/Jf9wcC+7jAxh59B3cOGxudWQXlA=";
     };
  +  patches = [
  +    (fetchpatch {
  +      name = "older-macos-fixes.patch";
  +      url = "https://github.com/microsoft/mimalloc/commit/40e0507a5959ee218f308d33aec212c3ebeef3bb.patch";
  +      sha256 = "15qx2a3axhhwbfzxdis98b8j14y9cfgca0i484aj2pjpqnm0pb8c";
  +    })
  +  ];
  +
  +  doCheck = true;
  +  preCheck = let
  +    ldLibraryPathEnv = if stdenv.isDarwin then "DYLD_LIBRARY_PATH" else "LD_LIBRARY_PATH";
  +  in ''
  +    export ${ldLibraryPathEnv}="$(pwd)/build:''${${ldLibraryPathEnv}}"
  +  '';
   
     nativeBuildInputs = [ cmake ninja ];
     cmakeFlags = [ "-DMI_INSTALL_TOPLEVEL=ON" ] ++ lib.optional secureBuild [ "-DMI_SECURE=ON" ];
  
positive.code: { lib, stdenv, fetchFromGitHub, cmake, ninja
  , secureBuild ? false
  }:
  
  
negative.code:     homepage    = "https://github.com/microsoft/mimalloc";
      license     = licenses.bsd2;
      platforms   = platforms.unix;
      maintainers = with maintainers; [ kamadorueda thoughtpolice ];
    };
  }
  