diff --git a/pkgs/development/ocaml-modules/gen/default.nix b/pkgs/development/ocaml-modules/gen/default.nix
index c023b590f7a..6cbbd4adc1b 100644
--- a/pkgs/development/ocaml-modules/gen/default.nix
+++ b/pkgs/development/ocaml-modules/gen/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchFromGitHub, ocaml, findlib, ocamlbuild, qtest, ounit }:
 
-let version = "0.3"; in
+let version = "0.4"; in
 
 stdenv.mkDerivation {
   name = "ocaml-gen-${version}";
@@ -9,7 +9,7 @@ stdenv.mkDerivation {
     owner = "c-cube";
     repo = "gen";
     rev = "${version}";
-    sha256 = "0xrnkcfa5q86ammf49j5hynw5563x5sa2mk7vqf7g097j1szif72";
+    sha256 = "041dga300fh1y6fi8y0fkri2qda406lf2dmbrgllazw3rp07zkzj";
   };
 
   buildInputs = [ ocaml findlib ocamlbuild qtest ounit ];