diff --git a/source/boost/boost/spirit/home/classic/iterator/impl/position_iterator.ipp b/source/boost/boost/spirit/home/classic/iterator/impl/position_iterator.ipp
index d473af1..fba6a36 100644
--- a/source/boost/boost/spirit/home/classic/iterator/impl/position_iterator.ipp
+++ b/source/boost/boost/spirit/home/classic/iterator/impl/position_iterator.ipp
@@ -125,7 +125,8 @@ public:
         main_iter_t,
         ForwardIterT,
         const_value_type,
-        boost::forward_traversal_tag
+        boost::forward_traversal_tag,
+        typename ForwardIterT::reference
     > type;
 };