diff --git a/include/boost/mpl/aux_/na_assert.hpp b/include/boost/mpl/aux_/na_assert.hpp
index 2d6d1f1..6df8a04 100644
--- a/include/boost/mpl/aux_/na_assert.hpp
+++ b/include/boost/mpl/aux_/na_assert.hpp
@@ -18,7 +18,7 @@
 #include <boost/mpl/aux_/config/msvc.hpp>
 #include <boost/mpl/aux_/config/workaround.hpp>
 
-#if !BOOST_WORKAROUND(_MSC_FULL_VER, < 140050601)    \
+#if !BOOST_WORKAROUND(_MSC_FULL_VER, <= 140050601)    \
     && !BOOST_WORKAROUND(__EDG_VERSION__, <= 243)
 #   include <boost/mpl/assert.hpp>
 #   define BOOST_MPL_AUX_ASSERT_NOT_NA(x) \