diff --git a/include/boost/type_traits/integral_constant.hpp b/include/boost/type_traits/integral_constant.hpp
index 3440dc5..1f95a63 100644
--- a/include/boost/type_traits/integral_constant.hpp
+++ b/include/boost/type_traits/integral_constant.hpp
@@ -67,7 +67,7 @@ namespace boost{
          static const char data[sizeof(long)] = { 0 };
          return dereference(reinterpret_cast<const mpl::integral_c<T, val>*>(&data));
       }
-      BOOST_CONSTEXPR operator T const() { return val; }
+      BOOST_CONSTEXPR operator T const()const { return val; }
    };
 
    template <class T, T val>
@@ -91,7 +91,7 @@ namespace boost{
          static const char data = 0;
          return dereference(reinterpret_cast<const mpl::bool_<val>*>(&data));
       }
-      BOOST_CONSTEXPR operator bool const() { return val; }
+      BOOST_CONSTEXPR operator bool const()const { return val; }
    };
 
    template <bool val>