diff --git a/include/boost/type_traits/detail/common_arithmetic_type.hpp b/include/boost/type_traits/detail/common_arithmetic_type.hpp
index a7aff03..92c16da 100644
--- a/include/boost/type_traits/detail/common_arithmetic_type.hpp
+++ b/include/boost/type_traits/detail/common_arithmetic_type.hpp
@@ -206,9 +206,11 @@ private:
 
     static bool cond();
 
+    BOOST_STATIC_CONSTANT(const int, selector = sizeof(select(cond() ? T() : U())));
+
 public:
 
-    typedef typename arithmetic_type< sizeof(select( cond()? T(): U() )) >::type type;
+    typedef typename arithmetic_type<selector>::type type;
 };
 
 } // namespace type_traits_detail