diff --git a/include/boost/mpl/integral_c.hpp b/include/boost/mpl/integral_c.hpp
index 6857a7f..d7abd12 100644
--- a/include/boost/mpl/integral_c.hpp
+++ b/include/boost/mpl/integral_c.hpp
@@ -40,7 +40,9 @@ template< bool C >
 struct integral_c<bool, C>
 {
     BOOST_STATIC_CONSTANT(bool, value = C);
+    typedef integral_c_tag tag;
     typedef integral_c type;
+    typedef bool value_type;
     operator bool() const { return this->value; }
 };
 BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE