diff --git a/pkgs/development/ocaml-modules/gen/default.nix b/pkgs/development/ocaml-modules/gen/default.nix
new file mode 100644
index 000000000000..0b8f4253e76c
--- /dev/null
+++ b/pkgs/development/ocaml-modules/gen/default.nix
@@ -0,0 +1,25 @@
+{ stdenv, fetchFromGitHub, ocaml, findlib, qtest, ounit }:
+
+let version = "0.3"; in
+
+stdenv.mkDerivation {
+  name = "ocaml-gen-${version}";
+
+  src = fetchFromGitHub {
+    owner = "c-cube";
+    repo = "gen";
+    rev = "${version}";
+    sha256 = "0xrnkcfa5q86ammf49j5hynw5563x5sa2mk7vqf7g097j1szif72";
+  };
+
+  buildInputs = [ ocaml findlib qtest ounit ];
+
+  createFindlibDestdir = true;
+
+  meta = {
+    homepage = https://github.com/c-cube/gen;
+    description = "Simple, efficient iterators for OCaml";
+    license = stdenv.lib.licenses.bsd3;
+    platforms = ocaml.meta.platforms;
+  };
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 605d39b6ac9f..e9fa46156647 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -4687,6 +4687,8 @@ let
 
     functory = callPackage ../development/ocaml-modules/functory { };
 
+    gen = callPackage ../development/ocaml-modules/gen { };
+
     herelib = callPackage ../development/ocaml-modules/herelib { };
 
     io-page = callPackage ../development/ocaml-modules/io-page { };