diff --git a/include/boost/intrusive_ptr.hpp b/include/boost/intrusive_ptr.hpp
index 9d713a8..24af067 100644
--- a/include/boost/intrusive_ptr.hpp
+++ b/include/boost/intrusive_ptr.hpp
@@ -14,6 +14,8 @@
 //  See http://www.boost.org/libs/smart_ptr/intrusive_ptr.html for documentation.
 //
 
+#include <boost/config.hpp>
+
 #ifdef BOOST_MSVC  // moved here to work around VC++ compiler crash
 # pragma warning(push)
 # pragma warning(disable:4284) // odd return type for operator->