diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 653184e..ea0e322 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -158,7 +158,7 @@ jobs:
       -  name: Run tests
          working-directory: build
          run: |
-            ctest -C Release --output-on-failure -E "XsmpSchedulerTest|PythonTest|xsmp_example_project1Test"
+            ctest -C Release --output-on-failure -E "XsmpSchedulerTest"
    python:
       name: '${{matrix.os}} :: Python ${{matrix.python-version}}'
       runs-on: ${{matrix.os}}
@@ -168,7 +168,7 @@ jobs:
             os:
             - ubuntu-latest
             - macos-latest
-#            - windows-latest
+            - windows-latest
             python-version:
             - '3.7'
             - '3.8'
@@ -189,4 +189,4 @@ jobs:
             max_attempts: 3
             retry_on: error
             timeout_minutes: 1
-            command: python -m pytest python -v
\ No newline at end of file
+            command: python -m pytest python -v
diff --git a/cmake/PytestAddTests.cmake b/cmake/PytestAddTests.cmake
index 0ca2ac1..34910f5 100644
--- a/cmake/PytestAddTests.cmake
+++ b/cmake/PytestAddTests.cmake
@@ -15,8 +15,8 @@ function(pytest_discover_tests_impl)
     
     # Use platform specific path separator (";" on windows else ":") and convert path to native platform (replace "/" by "\" on Windows)
     if (CMAKE_HOST_SYSTEM_NAME STREQUAL Windows)
-        string(REPLACE "][" "\\;" _LIBRARY_PATH "${_LIBRARY_PATH}")
-        string(REPLACE "][" "\\;" _PYTHON_PATH "${_PYTHON_PATH}")
+        string(REPLACE "][" "\\\\;" _LIBRARY_PATH "${_LIBRARY_PATH}")
+        string(REPLACE "][" "\\\\;" _PYTHON_PATH "${_PYTHON_PATH}")
         string(REPLACE "/" "\\\\" _LIBRARY_PATH "${_LIBRARY_PATH}")
         string(REPLACE "/" "\\\\" _PYTHON_PATH "${_PYTHON_PATH}")
     else()
@@ -29,7 +29,7 @@ function(pytest_discover_tests_impl)
         string(APPEND _content
             "add_test(\"${_TEST_GROUP_NAME}\" ${_PYTHON_EXECUTABLE} -m pytest \"${_WORKING_DIRECTORY}\"\)\n"
             "set_tests_properties(\"${_TEST_GROUP_NAME}\" PROPERTIES ENVIRONMENT \"${_LIB_ENV_PATH}=${_LIBRARY_PATH}\")\n"
-            "set_tests_properties(\"${_TEST_GROUP_NAME}\" APPEND PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
+            "set_tests_properties(\"${_TEST_GROUP_NAME}\" PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
         )
 
         foreach(env ${_ENVIRONMENT})
@@ -90,7 +90,7 @@ function(pytest_discover_tests_impl)
             string(APPEND _content
                 "add_test(\"${test_name}\" ${_PYTHON_EXECUTABLE} -m pytest \"${test_case}\")\n"
                 "set_tests_properties(\"${test_name}\" PROPERTIES ENVIRONMENT \"${_LIB_ENV_PATH}=${_LIBRARY_PATH}\")\n"
-                "set_tests_properties(\"${test_name}\" APPEND PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
+                "set_tests_properties(\"${test_name}\" PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
             )
 
             foreach(env ${_ENVIRONMENT})
@@ -105,7 +105,7 @@ function(pytest_discover_tests_impl)
             string(APPEND _content
                 "add_test(\"${_TEST_GROUP_NAME}\" ${_PYTHON_EXECUTABLE} -m pytest \"${_WORKING_DIRECTORY}\"\)\n"
                 "set_tests_properties(\"${_TEST_GROUP_NAME}\" PROPERTIES ENVIRONMENT \"${_LIB_ENV_PATH}=${_LIBRARY_PATH}\")\n"
-                "set_tests_properties(\"${_TEST_GROUP_NAME}\" APPEND PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
+                "set_tests_properties(\"${_TEST_GROUP_NAME}\" PROPERTIES ENVIRONMENT \"PYTHONPATH=${_PYTHON_PATH}\")\n"
             )
     
             foreach(env ${_ENVIRONMENT})
diff --git a/src/python/ecss_smp.h b/src/python/ecss_smp.h
index 5c0535b..26a8cbe 100644
--- a/src/python/ecss_smp.h
+++ b/src/python/ecss_smp.h
@@ -61,6 +61,15 @@
 namespace py = pybind11;
 
 namespace PYBIND11_NAMESPACE {
+
+template <typename itype>
+struct polymorphic_type_hook<itype, std::enable_if_t<std::is_base_of_v<Smp::IObject, itype>>> {
+    static const void *get(const itype *src, const std::type_info *&type) {
+        type = src ? &typeid(*src) : nullptr;
+        return static_cast<const Smp::IObject *>(src);
+    }
+};
+
 struct TypeHierarchy {
 
     template<typename T>
@@ -220,6 +229,7 @@ class SmpClass: public detail::generic_type {
         record.dealloc = dealloc;
         record.default_holder = true;
         record.module_local = true;
+        record.is_final = true;
 
         processHierarchy(IObjectHierarchy, obj, record);