diff --git a/include/boost/iterator/iterator_adaptor.hpp b/include/boost/iterator/iterator_adaptor.hpp
index 59ce07a..77d9990 100644
--- a/include/boost/iterator/iterator_adaptor.hpp
+++ b/include/boost/iterator/iterator_adaptor.hpp
@@ -261,7 +261,7 @@ namespace boost
       {
       }
 
-      Base base() const
+      Base const& base() const
         { return m_iterator; }
 
    protected: