diff --git a/include/boost/asio/detail/config.hpp b/include/boost/asio/detail/config.hpp
index 0f9e52d5..cc01e8ea 100644
--- a/include/boost/asio/detail/config.hpp
+++ b/include/boost/asio/detail/config.hpp
@@ -221,8 +221,7 @@
 #     define BOOST_ASIO_ERROR_CATEGORY_NOEXCEPT noexcept(true)
 #   endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
 #  endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
-# endif // defined(__GNUC__)
-# if defined(BOOST_ASIO_MSVC)
+# elif defined(BOOST_ASIO_MSVC)
 #  if (_MSC_VER >= 1900)
 #   define BOOST_ASIO_ERROR_CATEGORY_NOEXCEPT noexcept(true)
 #  endif // (_MSC_VER >= 1900)