diff --git a/include/boost/type_traits/common_type.hpp b/include/boost/type_traits/common_type.hpp
index 00129d1..2d53c25 100644
--- a/include/boost/type_traits/common_type.hpp
+++ b/include/boost/type_traits/common_type.hpp
@@ -24,8 +24,10 @@
 #endif
 
 //----------------------------------------------------------------------------//
-#if defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF) && !defined(BOOST_TYPEOF_SILENT)
-#define BOOST_TYPEOF_SILENT
+#if defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_COMMON_TYPE_DONT_USE_TYPEOF)
+#  ifndef BOOST_TYPEOF_SILENT
+#     define BOOST_TYPEOF_SILENT
+#  endif
 #include <boost/typeof/typeof.hpp>   // boost wonders never cease!
 #endif