diff --git a/include/boost/optional.hpp b/include/boost/optional.hpp
index 7dbd9a6..9a5c446 100644
--- a/include/boost/optional.hpp
+++ b/include/boost/optional.hpp
@@ -57,7 +57,7 @@ namespace boost
          union dummy_u
          {
              char data[ sizeof(T) ];
-             type_with_alignment< ::boost::alignment_of<T>::value > aligner_;
+             type_with_alignment< ::boost::alignment_of<T>::value >::type aligner_;
          } dummy_ ;
 
       public: