diff --git a/pkgs/development/ocaml-modules/iomux/default.nix b/pkgs/development/ocaml-modules/iomux/default.nix
new file mode 100644
index 000000000000..f1dc827a32d0
--- /dev/null
+++ b/pkgs/development/ocaml-modules/iomux/default.nix
@@ -0,0 +1,34 @@
+{ lib
+, fetchurl
+, buildDunePackage
+, dune-configurator
+, alcotest
+}:
+
+buildDunePackage rec {
+  pname = "iomux";
+  version = "0.3";
+
+  minimalOCamlVersion = "4.08";
+  duneVersion = "3";
+
+  src = fetchurl {
+    url = "https://github.com/haesbaert/ocaml-${pname}/releases/download/v${version}/${pname}-${version}.tbz";
+    sha256 = "zNJ3vVOv0BEpHLiC8Y610F87uiMlfYNo28ej0H+EU+c=";
+  };
+
+  buildInputs = [
+    dune-configurator
+  ];
+
+  checkInputs = [
+    alcotest
+  ];
+
+  meta = {
+    homepage = "https://github.com/haesbaert/ocaml-${pname}";
+    description = "IO Multiplexers for OCaml";
+    license = with lib.licenses; [ isc ];
+    maintainers = with lib.maintainers; [ toastal ];
+  };
+}
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 05be94f39eaf..bf1d3eb65887 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -663,6 +663,8 @@ let
 
     integers_stubs_js = callPackage ../development/ocaml-modules/integers_stubs_js { };
 
+    iomux = callPackage ../development/ocaml-modules/iomux { };
+
     io-page = callPackage ../development/ocaml-modules/io-page { };
 
     ipaddr = callPackage ../development/ocaml-modules/ipaddr { };