diff --git a/pkgs/development/ocaml-modules/bytesrw/default.nix b/pkgs/development/ocaml-modules/bytesrw/default.nix
new file mode 100644
index 000000000000..4894c14df29f
--- /dev/null
+++ b/pkgs/development/ocaml-modules/bytesrw/default.nix
@@ -0,0 +1,48 @@
+{
+  lib,
+  fetchzip,
+  libblake3,
+  libmd,
+  xxHash,
+  zlib,
+  zstd,
+  buildTopkgPackage,
+}:
+
+buildTopkgPackage rec {
+  pname = "bytesrw";
+  version = "0.1.0";
+
+  minimalOCamlVersion = "4.14.0";
+
+  src = fetchzip {
+    url = "https://erratique.ch/software/bytesrw/releases/bytesrw-${version}.tbz";
+    hash = "sha256-leH3uo5Q8ba22A/Mbl9pio0tW/IxCTGp77Cra7l4D80=";
+  };
+
+  # docs say these are optional, but buildTopkgPackage doesn’t handle missing
+  # dependencies
+
+  buildInputs = [
+    libblake3
+    libmd
+    xxHash
+    zlib
+    zstd
+  ];
+
+  meta = {
+    description = "composable, memory efficient, byte stream readers and writers compatible with effect-based concurrency";
+    longDescription = ''
+      Bytesrw extends the OCaml Bytes module with composable, memory efficient,
+      byte stream readers and writers compatible with effect-based concurrency.
+
+      Except for byte slice life-times, these abstractions intentionnaly
+      separate away ressource management and the specifics of reading and
+      writing bytes.
+    '';
+    homepage = "https://erratique.ch/software/bytesrw";
+    license = 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 b77ac0a0ac67..ba1c955db65b 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -141,6 +141,8 @@ let
 
         bwd = callPackage ../development/ocaml-modules/bwd { };
 
+        bytesrw = callPackage ../development/ocaml-modules/bytesrw { };
+
         bytestring = callPackage ../development/ocaml-modules/bytestring { };
 
         bz2 = callPackage ../development/ocaml-modules/bz2 { };