diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 4c8bc76254..a30337e12d 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -231,6 +231,16 @@ jobs:
       with:
         python-version: '3.11.4'
 
+    # virtualenv is no longer included as of 20240929.1 runner so
+    # install it ourselves. See
+    # https://github.com/actions/runner-images/issues/10749.
+    #
+    # Note that it is the builds of sdist and wheel that require virtualenv
+    # not the explicit dependencies of pyktx.
+    - name: Install Python virtualenv
+      if: matrix.options.py == 'ON' && matrix.check_mkvk != 'ONLY'
+      run: pip install virtualenv
+
     - name: Init CTS submodule
       if: matrix.options.tools_cts =='ON'
       run:
diff --git a/interface/python_binding/CMakeLists.txt b/interface/python_binding/CMakeLists.txt
index b2c4051434..1f26c8a198 100644
--- a/interface/python_binding/CMakeLists.txt
+++ b/interface/python_binding/CMakeLists.txt
@@ -88,6 +88,8 @@ add_custom_command(
             LIBKTX_INCLUDE_DIR=${CMAKE_SOURCE_DIR}/include
             LIBKTX_LIB_DIR=${LIBKTX_LIB_DIR}
             LIBKTX_VERSION=${KTX_VERSION_NORMALIZED}
+        # Bulding sdist requires a virtual env. I have not found a
+        # a way via find_package to ensure venv support is installed.
         ${PYTHON_EXECUTABLE} -m build --sdist --outdir ${DIST_DIR}
     WORKING_DIRECTORY
         ${SOURCE_DIR}
@@ -103,6 +105,7 @@ add_custom_command(
             LIBKTX_INCLUDE_DIR=${CMAKE_SOURCE_DIR}/include
             LIBKTX_LIB_DIR=${LIBKTX_LIB_DIR}
             LIBKTX_VERSION=${KTX_VERSION_NORMALIZED}
+        # Ditto with sdist venv comment.
         ${PYTHON_EXECUTABLE} -m build --wheel --outdir ${DIST_DIR}
     WORKING_DIRECTORY
         ${SOURCE_DIR}