diff --git a/Parallel/Core/Testing/Cxx/CMakeLists.txt b/Parallel/Core/Testing/Cxx/CMakeLists.txt
index 1eceefb0c63f3292f5ce5469ae5daacf37f83371..84a4eaaaa15e738b133022ebe5d7a3475923c8c0 100644
--- a/Parallel/Core/Testing/Cxx/CMakeLists.txt
+++ b/Parallel/Core/Testing/Cxx/CMakeLists.txt
@@ -6,7 +6,8 @@ vtk_add_test_cxx(vtkParallelCoreCxxTests tests
   )
 vtk_test_cxx_executable(vtkParallelCoreCxxTests tests)
 
-if (Python3_EXECUTABLE)
+if (Python3_EXECUTABLE AND
+    NOT CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
   vtk_module_test_executable(
     vtkParallelCore-TestSocketCommunicator TestSocketCommunicator.cxx)
 
diff --git a/Rendering/Parallel/Testing/Cxx/CMakeLists.txt b/Rendering/Parallel/Testing/Cxx/CMakeLists.txt
index b2e45a84436878e01e7ddf80380c6d937d0348dc..c4ec9bae373e9f1e61d38d1d01b748001de76c58 100644
--- a/Rendering/Parallel/Testing/Cxx/CMakeLists.txt
+++ b/Rendering/Parallel/Testing/Cxx/CMakeLists.txt
@@ -17,7 +17,8 @@ set(all_tests
   )
 vtk_test_cxx_executable(vtkRenderingParallelCxxTests-MPI all_tests)
 
-if (Python3_EXECUTABLE)
+if (Python3_EXECUTABLE AND
+    NOT CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
   vtk_module_test_executable(
     vtkRenderingParallel-TestClientServerRendering TestClientServerRendering.cxx)