diff --git a/include/boost/type_traits/conversion_traits.hpp b/include/boost/type_traits/conversion_traits.hpp
index c94a4a6..3d640a5 100644
--- a/include/boost/type_traits/conversion_traits.hpp
+++ b/include/boost/type_traits/conversion_traits.hpp
@@ -200,6 +200,12 @@ public:
    void foo(); // avoid warning about all members being private
 };
 
+#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
+//  A definition is required even for integral static constants
+template <class From, class To>
+const bool is_convertible<From, To>::value;
+#endif
+
 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 template <class From>
 struct is_convertible<From, void>
diff --git a/include/boost/type_traits/same_traits.hpp b/include/boost/type_traits/same_traits.hpp
index 5c9fef1..6cc4228 100644
--- a/include/boost/type_traits/same_traits.hpp
+++ b/include/boost/type_traits/same_traits.hpp
@@ -41,6 +41,15 @@ template <typename T>
 struct is_same<T, T>
 { BOOST_STATIC_CONSTANT(bool, value = true); };
 
+#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
+//  A definition is required even for integral static constants
+template <typename T, typename U>
+const bool is_same<T, U>::value;
+
+template <typename T>
+const bool is_same<T, T>::value;
+#endif
+
 #else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 
 #ifdef BOOST_MSVC