diff --git a/include/boost/bind.hpp b/include/boost/bind.hpp
index dff1854..15ab8c7 100644
--- a/include/boost/bind.hpp
+++ b/include/boost/bind.hpp
@@ -1,8 +1,8 @@
 #ifndef BOOST_BIND_HPP_INCLUDED
 #define BOOST_BIND_HPP_INCLUDED
 
-#if _MSC_VER >= 1020
-#pragma once
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
 #endif
 
 //
diff --git a/include/boost/bind/arg.hpp b/include/boost/bind/arg.hpp
index c0c32d2..cac6521 100644
--- a/include/boost/bind/arg.hpp
+++ b/include/boost/bind/arg.hpp
@@ -1,8 +1,8 @@
 #ifndef BOOST_BIND_ARG_HPP_INCLUDED
 #define BOOST_BIND_ARG_HPP_INCLUDED
 
-#if _MSC_VER >= 1020
-#pragma once
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
 #endif
 
 //
diff --git a/include/boost/bind/placeholders.hpp b/include/boost/bind/placeholders.hpp
index 3d4ed27..2c05a19 100644
--- a/include/boost/bind/placeholders.hpp
+++ b/include/boost/bind/placeholders.hpp
@@ -1,8 +1,8 @@
 #ifndef BOOST_BIND_PLACEHOLDERS_HPP_INCLUDED
 #define BOOST_BIND_PLACEHOLDERS_HPP_INCLUDED
 
-#if _MSC_VER >= 1020
-#pragma once
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
 #endif
 
 //