diff --git a/include/boost/regex/config.hpp b/include/boost/regex/config.hpp
index a9acbe29..87bc085b 100644
--- a/include/boost/regex/config.hpp
+++ b/include/boost/regex/config.hpp
@@ -255,7 +255,7 @@
  *
  ****************************************************************************/
 
-#if defined(BOOST_MSVC) && defined(_MSC_EXTENSIONS)
+#if defined(_MSC_VER) && defined(_MSC_EXTENSIONS)
 #if defined(_DEBUG) || defined(__MSVC_RUNTIME_CHECKS) || defined(_MANAGED) || defined(BOOST_REGEX_NO_FASTCALL)
 #  define BOOST_REGEX_CALL __cdecl
 #else