diff --git a/pkgs/by-name/un/units-llnl/package.nix b/pkgs/by-name/un/units-llnl/package.nix
new file mode 100644
index 000000000000..fcba27fb936c
--- /dev/null
+++ b/pkgs/by-name/un/units-llnl/package.nix
@@ -0,0 +1,42 @@
+{
+  lib,
+  stdenv,
+  fetchFromGitHub,
+  cmake,
+
+  # This is the baseType needed by scipp - the main package that depends on
+  # this package.
+  baseType ? "uint64_t",
+}:
+
+stdenv.mkDerivation (finalAttrs: {
+  pname = "units-llnl";
+  version = "0.13.1";
+
+  src = fetchFromGitHub {
+    owner = "LLNL";
+    repo = "units";
+    tag = "v${finalAttrs.version}";
+    hash = "sha256-thJnBT+wQPF9obzXk/T6H9lvPEAH5REx3YhBXEd7n7c=";
+    fetchSubmodules = true;
+  };
+
+  nativeBuildInputs = [
+    cmake
+  ];
+  cmakeFlags = [
+    (lib.cmakeBool "BUILD_SHARED_LIBS" true)
+    (lib.cmakeFeature "UNITS_BASE_TYPE" baseType)
+  ];
+  doCheck = true;
+
+  meta = {
+    description = "Run-time C++ library for working with units of measurement and conversions between them and with string representations of units and measurements";
+    homepage = "https://github.com/llnl/units";
+    changelog = "https://github.com/llnl/units/blob/${finalAttrs.src.tag}/CHANGELOG.md";
+    license = lib.licenses.bsd3;
+    maintainers = with lib.maintainers; [ doronbehar ];
+    mainProgram = "units-llnl";
+    platforms = lib.platforms.all;
+  };
+})