--- join_iterator_original.hpp	2012-12-03 12:40:59.342140500 +0100
+++ join_iterator.hpp	2013-04-18 13:46:57.690758900 +0200
@@ -143,9 +143,13 @@
                                     typename iterator_reference<Iterator2>::type
                                 >::type
                             >::value,
-                            typename add_const<
-                                typename iterator_reference<Iterator2>::type
-                            >::type,
+							typename add_reference< 
+								typename add_const<
+									typename remove_reference<
+										typename iterator_reference<Iterator2>::type
+									>::type
+								>::type
+							>::type,
                             typename iterator_reference<Iterator1>::type
                         >::type
                     >::type