1 files changed, 18 insertions, 4 deletions
diff --git a/pkgs/development/compilers/mezzo/default.nix b/pkgs/development/compilers/mezzo/default.nix
index 183640f5985d..a0fe441b1538 100644
--- a/pkgs/development/compilers/mezzo/default.nix
+++ b/pkgs/development/compilers/mezzo/default.nix
@@ -1,16 +1,30 @@
-{stdenv, fetchurl, ocaml, findlib, menhir, yojson, ulex, pprint, fix, functory}:
+{ stdenv, fetchFromGitHub, ocaml, findlib, menhir, yojson, ulex, pprint, fix, functory }:
+
+let
+  check-ocaml-version = with stdenv.lib; versionAtLeast (getVersion ocaml);
+in
+
+assert check-ocaml-version "4";
 
 stdenv.mkDerivation {
 
   name = "mezzo-0.0.m8";
 
-  src = fetchurl {
-    url = https://github.com/protz/mezzo/archive/m8.tar.gz;
-    sha256 = "17mfapgqp8ssa5x9blv72zg9l561zbiwv3ikwi6nl9dd36lwkkc6";
+  src = fetchFromGitHub {
+    owner = "protz";
+    repo = "mezzo";
+    rev = "m8";
+    sha256 = "0yck5r6di0935s3iy2mm9538jkf77ssr789qb06ms7sivd7g3ip6";
   };
 
   buildInputs = [ ocaml findlib yojson menhir ulex pprint fix functory ];
 
+  # Sets warning 3 as non-fatal
+  prePatch = stdenv.lib.optionalString (check-ocaml-version "4.02") ''
+    substituteInPlace myocamlbuild.pre.ml \
+    --replace '@1..3' '@1..2+3'
+  '';
+
   createFindlibDestdir = true;
 
   postInstall = ''