diff --git a/pkgs/development/ocaml-modules/ohex/default.nix b/pkgs/development/ocaml-modules/ohex/default.nix
new file mode 100644
index 000000000000..49bf6005c686
--- /dev/null
+++ b/pkgs/development/ocaml-modules/ohex/default.nix
@@ -0,0 +1,25 @@
+{
+  lib,
+  fetchurl,
+  buildDunePackage,
+  alcotest,
+}:
+
+buildDunePackage rec {
+  pname = "ohex";
+  version = "0.2.0";
+
+  src = fetchurl {
+    url = "https://github.com/ocaml/opam-source-archives/raw/main/ohex-${version}.tar.gz";
+    hash = "sha256-prV7rbo0sAx3S2t4YtjniJEVq43uLXK8ZMsqoMzn2Ow=";
+  };
+
+  doCheck = true;
+  checkInputs = [ alcotest ];
+
+  meta = {
+    description = "Hexadecimal encoding and decoding";
+    license = lib.licenses.bsd2;
+    maintainers = [ lib.maintainers.vbgl ];
+  };
+}
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index e9ce03cc678a..ef556b0f52e3 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -1407,6 +1407,8 @@ let
 
     ogg = callPackage ../development/ocaml-modules/ogg { };
 
+    ohex = callPackage ../development/ocaml-modules/ohex { };
+
     ojs = callPackage ../development/ocaml-modules/gen_js_api/ojs.nix { };
 
     omd = callPackage ../development/ocaml-modules/omd { };