diff --git a/CMakeLists.txt b/CMakeLists.txt
index afe375041..eefaf4b47 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -108,7 +108,8 @@ endif(CMAKE_COMPILER_IS_GNUCXX)
 if(MSVC)
   # C4127 - conditional expression is constant
   # C4505 - unreferenced local function has been removed
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc /W4 /wd4127 /wd4505")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc /wd4127 /wd4505")
+  string(REGEX REPLACE "/W[0-9]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
   option(EIGEN_TEST_SSE2 "Enable/Disable SSE2 in tests/examples" OFF)
   if(EIGEN_TEST_SSE2)
     if(NOT CMAKE_CL_64)