diff --git a/include/nana/c++defines.hpp b/include/nana/c++defines.hpp
index 70db8f8f..98c23dc4 100644
--- a/include/nana/c++defines.hpp
+++ b/include/nana/c++defines.hpp
@@ -202,6 +202,7 @@
 #undef _nana_cxx_constexpr_if
 #if (defined(_MSC_VER) && (_MSC_VER >= 1912) && defined(_MSVC_LANG) && _MSVC_LANG>= 201703)
 #	define _nana_cxx_constexpr_if
+#	define _nana_cxx_folding_expression
 #endif