anchor.diff:  }:
   
   let
  -  version = "4.1.0";
  +  version = "4.1.2";
   
     src = fetchFromGitHub {
       owner  = "opencv";
       repo   = "opencv";
       rev    = version;
  -    sha256 = "0m1f51m11iz4vxfrmnhawksd669ld247rlfdq5fhkvfk3r7aidw6";
  +    sha256 = "0c98ziwvfrzdzwn52a36d37n5rac8zmxq2jn479bzfaii1bib8xx";
     };
   
     contribSrc = fetchFromGitHub {
       owner  = "opencv";
       repo   = "opencv_contrib";
       rev    = version;
  -    sha256 = "1phmmba96m5znjf3wxwhxavgzgp3bs5qqsjk9ay1i63rdacz4vlf";
  +    sha256 = "10ryyxhggin5dk5glf4ycyrfryqf50f4bs10biv6nxlrrinm2di4";
     };
   
     # Contrib must be built in order to enable Tesseract support:
  
positive.code:   ade = rec {
      src = fetchurl {
        url = "https://github.com/opencv/ade/archive/${name}";
        sha256 = "1r85vdkvcka7bcxk69pd0ai4hld4iakpj4xl0xbinx3p9pv5a4l8";
      };
      name = "v0.1.1d.zip";
      md5 = "37479d90e3a5d47f132f512b22cbe206";
      dst = ".cache/ade";
    };
  
  
negative.code:   postUnpack = lib.optionalString buildContrib ''
      cp --no-preserve=mode -r "${contribSrc}/modules" "$NIX_BUILD_TOP/source/opencv_contrib"
    '';
  
    # This prevents cmake from using libraries in impure paths (which
    # causes build failure on non NixOS)
  