diff --git a/pkgs/development/ocaml-modules/kcas/default.nix b/pkgs/development/ocaml-modules/kcas/default.nix
new file mode 100644
index 000000000000..2d840b9a750b
--- /dev/null
+++ b/pkgs/development/ocaml-modules/kcas/default.nix
@@ -0,0 +1,26 @@
+{ lib, buildDunePackage, fetchurl
+, domain-local-await, domain-local-timeout
+, alcotest
+}:
+
+buildDunePackage rec {
+  pname = "kcas";
+  version = "0.6.1";
+
+  src = fetchurl {
+    url = "https://github.com/ocaml-multicore/kcas/releases/download/${version}/kcas-${version}.tbz";
+    hash = "sha256-u3Z8uAvITRUhOcB2EUYjWtpxIFJMvm2O/kyNr/AELWI=";
+  };
+
+  propagatedBuildInputs = [ domain-local-await domain-local-timeout ];
+
+  doCheck = true;
+  checkInputs = [ alcotest ];
+
+  meta = {
+    homepage = "https://github.com/ocaml-multicore/kcas";
+    description = "STM based on lock-free MCAS";
+    license = lib.licenses.isc;
+    maintainers = [ lib.maintainers.vbgl ];
+  };
+}
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 1e12fff7ff1b..984c5791ea04 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -799,6 +799,8 @@ let
 
     kafka_lwt = callPackage ../development/ocaml-modules/kafka/lwt.nix { };
 
+    kcas = callPackage ../development/ocaml-modules/kcas { };
+
     ke = callPackage ../development/ocaml-modules/ke { };
 
     kicadsch = callPackage ../development/ocaml-modules/kicadsch { };