diff --git a/include/boost/type_traits/integral_constant.hpp b/include/boost/type_traits/integral_constant.hpp
index 6c43ece..b8e6250 100644
--- a/include/boost/type_traits/integral_constant.hpp
+++ b/include/boost/type_traits/integral_constant.hpp
@@ -67,6 +67,7 @@ namespace boost{
    template <bool val>
    struct integral_constant<bool, val>
    {
+      typedef mpl::integral_c_tag tag;
       typedef integral_constant<bool, val> type;
       static const bool value = val;