diff --git a/include/boost/container/detail/version_type.hpp b/include/boost/container/detail/version_type.hpp
index c2531cc..58e9da6 100644
--- a/include/boost/container/detail/version_type.hpp
+++ b/include/boost/container/detail/version_type.hpp
@@ -39,24 +39,14 @@ struct version_type
     : public dtl::integral_constant<unsigned, V>
 {
     typedef T type;
-
-    version_type(const version_type<T, 0>&);
 };
 
 namespace impl{
 
-template <class T,
-          bool = dtl::is_convertible<version_type<T, 0>, typename T::version>::value>
-struct extract_version
-{
-   static const unsigned value = 1;
-};
-
 template <class T>
-struct extract_version<T, true>
-{
-   static const unsigned value = T::version::value;
-};
+struct extract_version
+   : T::version
+{};
 
 template <class T>
 struct has_version