diff --git a/include/boost/integer_traits.hpp b/include/boost/integer_traits.hpp
index 34b3570..e31a638 100644
--- a/include/boost/integer_traits.hpp
+++ b/include/boost/integer_traits.hpp
@@ -227,7 +227,7 @@ class integer_traits< ::boost::ulong_long_type>
 template<>
 class integer_traits< ::boost::long_long_type>
   : public std::numeric_limits< ::boost::long_long_type>,
-    public detail::integer_traits_base< ::boost::long_long_type, (1LL << (sizeof(::boost::long_long_type) - 1)), ~(1LL << (sizeof(::boost::long_long_type) - 1))>
+    public detail::integer_traits_base< ::boost::long_long_type, (1LL << (sizeof(::boost::long_long_type) * CHAR_BIT - 1)), ~(1LL << (sizeof(::boost::long_long_type) * CHAR_BIT - 1))>
 { };
 
 template<>