diff --git a/include/boost/type_traits/common_type.hpp b/include/boost/type_traits/common_type.hpp
index 6e54290..f316ad9 100644
--- a/include/boost/type_traits/common_type.hpp
+++ b/include/boost/type_traits/common_type.hpp
@@ -48,7 +48,7 @@
 #include <boost/type_traits/remove_cv.hpp>
 #endif
 #include <boost/mpl/if.hpp>
-//#include <boost/type_traits/declval.hpp>
+#include <boost/utility/declval.hpp>
 #include <boost/type_traits/add_rvalue_reference.hpp>
 
 //----------------------------------------------------------------------------//