diff --git a/.github/workflows/main-stock-ubuntu.yml b/.github/workflows/main-stock-ubuntu.yml
index 1f530a86..ab03c76f 100644
--- a/.github/workflows/main-stock-ubuntu.yml
+++ b/.github/workflows/main-stock-ubuntu.yml
@@ -99,6 +99,9 @@ jobs:
           echo "::group::xo-unit build"
           cmake --build .build -- xo-unit
 
+          echo "::group::xo-pyunit build"
+          cmake --build .build -- xo-pyunit
+
           echo "::group::xo build (catch all)"
           cmake --build .build #--verbose
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ced5d395..4287923a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -77,7 +77,7 @@ add_subdirectory(xo-reflect)
 add_subdirectory(xo-pyreflect)
 add_subdirectory(xo-ratio)
 add_subdirectory(xo-unit)
-#add_subdirectory(xo-pyunit)
+add_subdirectory(xo-pyunit)
 #add_subdirectory(xo-expression)
 #add_subdirectory(xo-pyexpression)
 #add_subdirectory(xo-tokenizer)
diff --git a/default.nix b/default.nix
index 78ac8b58..533f8014 100644
--- a/default.nix
+++ b/default.nix
@@ -50,7 +50,7 @@ let
           xo-pyreflect      = self.callPackage pkgs/xo-pyreflect.nix      {};
           xo-ratio          = self.callPackage pkgs/xo-ratio.nix          {};
           xo-unit           = self.callPackage pkgs/xo-unit.nix           {};
-#          xo-pyunit         = self.callPackage pkgs/xo-pyunit.nix         {};
+          xo-pyunit         = self.callPackage pkgs/xo-pyunit.nix         {};
 #          xo-expression     = self.callPackage pkgs/xo-expression.nix     {};
 #          xo-pyexpression   = self.callPackage pkgs/xo-pyexpression.nix   {};
 #          xo-tokenizer      = self.callPackage pkgs/xo-tokenizer.nix      {};
diff --git a/pkgs/xo-pyunit.nix b/pkgs/xo-pyunit.nix
new file mode 100644
index 00000000..5aa837cc
--- /dev/null
+++ b/pkgs/xo-pyunit.nix
@@ -0,0 +1,39 @@
+{
+  # nixpkgs dependencies
+  stdenv, cmake, catch2, # ... other deps here
+
+  # xo dependencies
+  xo-cmake, #xo-refcnt,
+  xo-pyutil, #xo-reflect,
+  xo-unit,
+
+  # args
+
+  #   attrset for fetching source code.
+  #    { type, owner, repo, ref }
+  #
+  #   e.g. type="github", owner="rconybea", repo="cmake-examples", ref="ex1b"
+  #
+  #   see [[../flake.nix]]
+  #
+  #cmake-examples-ex1-path
+
+  # someconfigurationoption ? false
+} :
+
+stdenv.mkDerivation (finalattrs:
+  {
+    name = "xo-pyunit";
+    version = "1.0";
+
+    src = ../xo-pyunit;
+
+    cmakeFlags = ["-DCMAKE_MODULE_PATH=${xo-cmake}/share/cmake"];
+    doCheck = true;
+    nativeBuildInputs = [ cmake catch2 xo-cmake ];
+    propagatedBuildInputs = [
+      #xo-refcnt
+      xo-pyutil
+      #xo-reflect
+      xo-unit ];
+  })
diff --git a/pkgs/xo-userenv.nix b/pkgs/xo-userenv.nix
index a8a0dbf1..655017f7 100644
--- a/pkgs/xo-userenv.nix
+++ b/pkgs/xo-userenv.nix
@@ -70,7 +70,7 @@ buildEnv {
             xo-pyreflect
             xo-ratio
             xo-unit
-#            xo-pyunit
+            xo-pyunit
 #            xo-expression
 #            xo-pyexpression
 #            xo-tokenizer