diff --git a/include/boost/config/compiler/visualc.hpp b/include/boost/config/compiler/visualc.hpp
index 092252e3..4c47b120 100644
--- a/include/boost/config/compiler/visualc.hpp
+++ b/include/boost/config/compiler/visualc.hpp
@@ -185,6 +185,7 @@
 #  define BOOST_NO_CXX14_GENERIC_LAMBDAS
 #  define BOOST_NO_CXX14_DIGIT_SEPARATORS
 #  define BOOST_NO_CXX11_THREAD_LOCAL
+#  define BOOST_NO_CXX11_UNRESTRICTED_UNION
 #endif
 // C++11 features supported by VC++ 14 update 3 (aka 2015)
 //