diff --git a/include/boost/unordered/detail/hash_table.hpp b/include/boost/unordered/detail/hash_table.hpp
index c6ded509..04696176 100644
--- a/include/boost/unordered/detail/hash_table.hpp
+++ b/include/boost/unordered/detail/hash_table.hpp
@@ -87,7 +87,7 @@ namespace boost {
             1610612741ul, 3221225473ul, 4294967291ul };
 
         template<typename T>
-        std::ptrdiff_t const prime_list_template<T>::length = 28;
+        std::ptrdiff_t const prime_list_template<T>::length = 40;
 
         typedef prime_list_template<std::size_t> prime_list;