diff --git a/pkgs/development/ocaml-modules/bytestring/default.nix b/pkgs/development/ocaml-modules/bytestring/default.nix
new file mode 100644
index 000000000000..3714846ee6b5
--- /dev/null
+++ b/pkgs/development/ocaml-modules/bytestring/default.nix
@@ -0,0 +1,45 @@
+{ lib
+, buildDunePackage
+, fetchurl
+, ppxlib
+, rio
+, sedlex
+, spices
+, uutf
+, qcheck
+}:
+
+buildDunePackage rec {
+  pname = "bytestring";
+  version = "0.0.8";
+
+  minimalOCamlVersion = "5.1";
+
+  src = fetchurl {
+    url = "https://github.com/riot-ml/riot/releases/download/${version}/riot-${version}.tbz";
+    hash = "sha256-SsiDz53b9bMIT9Q3IwDdB3WKy98WSd9fiieU41qZpeE=";
+  };
+
+  propagatedBuildInputs = [
+    ppxlib
+    sedlex
+    spices
+    rio
+    uutf
+  ];
+
+  checkInputs = [
+    qcheck
+  ];
+
+  # Checks fail with OCaml 5.2
+  doCheck = false;
+
+  meta = {
+    description = "Efficient, immutable, pattern-matchable, UTF friendly byte strings";
+    homepage = "https://github.com/riot-ml/riot";
+    license = lib.licenses.mit;
+    maintainers = with lib.maintainers; [ ];
+  };
+}
+
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index bd5e5523c1dd..4bef08626b29 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -119,6 +119,8 @@ let
 
     bwd = callPackage ../development/ocaml-modules/bwd { };
 
+    bytestring = callPackage ../development/ocaml-modules/bytestring { };
+
     bz2 = callPackage ../development/ocaml-modules/bz2 { };
 
     ### C ###