diff --git a/build_files/build_environment/cmake/ispc.cmake b/build_files/build_environment/cmake/ispc.cmake
index 160088bc16f..7fd8ac34b0e 100644
--- a/build_files/build_environment/cmake/ispc.cmake
+++ b/build_files/build_environment/cmake/ispc.cmake
@@ -6,6 +6,7 @@ if(WIN32)
     -DBISON_EXECUTABLE=${LIBDIR}/flexbison/win_bison.exe
     -DM4_EXECUTABLE=${DOWNLOAD_DIR}/mingw/mingw64/msys/1.0/bin/m4.exe
     -DARM_ENABLED=Off
+    -DPython3_FIND_REGISTRY=NEVER
   )
 elseif(APPLE)
   # Use bison and flex installed via Homebrew.
diff --git a/build_files/build_environment/cmake/openimagedenoise.cmake b/build_files/build_environment/cmake/openimagedenoise.cmake
index 3612e91a690..81fe8e79f09 100644
--- a/build_files/build_environment/cmake/openimagedenoise.cmake
+++ b/build_files/build_environment/cmake/openimagedenoise.cmake
@@ -16,6 +16,7 @@ if(WIN32)
     ${OIDN_EXTRA_ARGS}
     -DTBB_DEBUG_LIBRARY=${LIBDIR}/tbb/lib/tbb.lib
     -DTBB_DEBUG_LIBRARY_MALLOC=${LIBDIR}/tbb/lib/tbbmalloc.lib
+    -DPython3_FIND_REGISTRY=NEVER
   )
 else()
   set(OIDN_EXTRA_ARGS