diff --git a/include/boost/checked_delete.hpp b/include/boost/checked_delete.hpp
index 480c041..d7f5212 100644
--- a/include/boost/checked_delete.hpp
+++ b/include/boost/checked_delete.hpp
@@ -1,6 +1,8 @@
 #ifndef BOOST_CHECKED_DELETE_HPP_INCLUDED
 #define BOOST_CHECKED_DELETE_HPP_INCLUDED
 
+// MS compatible compilers support #pragma once
+
 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
 # pragma once
 #endif
diff --git a/include/boost/ref.hpp b/include/boost/ref.hpp
index 52f01cd..8ff5725 100644
--- a/include/boost/ref.hpp
+++ b/include/boost/ref.hpp
@@ -1,13 +1,15 @@
 #ifndef BOOST_REF_HPP_INCLUDED
-# define BOOST_REF_HPP_INCLUDED
+#define BOOST_REF_HPP_INCLUDED
 
-# if _MSC_VER+0 >= 1020
-#  pragma once
-# endif
+// MS compatible compilers support #pragma once
 
-# include <boost/config.hpp>
-# include <boost/utility/addressof.hpp>
-# include <boost/mpl/bool.hpp>
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <boost/config.hpp>
+#include <boost/utility/addressof.hpp>
+#include <boost/mpl/bool.hpp>
 
 //
 //  ref.hpp - ref/cref, useful helper functions