diff --git a/include/boost/smart_ptr/detail/spinlock_pool.hpp b/include/boost/smart_ptr/detail/spinlock_pool.hpp
index 0e2e08a..f09d5c6 100644
--- a/include/boost/smart_ptr/detail/spinlock_pool.hpp
+++ b/include/boost/smart_ptr/detail/spinlock_pool.hpp
@@ -41,7 +41,11 @@ public:
 
     static spinlock & spinlock_for( void const * pv )
     {
+#if defined(__VMS) && __INITIAL_POINTER_SIZE == 64  
+        std::size_t i = reinterpret_cast< unsigned long long >( pv ) % 41;
+#else  
         std::size_t i = reinterpret_cast< std::size_t >( pv ) % 41;
+#endif  
         return pool_[ i ];
     }