diff --git a/doc/reverse_iterator_ref.rst b/doc/reverse_iterator_ref.rst
index 2e56040..36b93d6 100644
--- a/doc/reverse_iterator_ref.rst
+++ b/doc/reverse_iterator_ref.rst
@@ -40,7 +40,9 @@ convertible to ``input_iterator_tag``.
 ``reverse_iterator`` requirements
 .................................
 
-``Iterator`` must be a model of Bidirectional Traversal Iterator.
+``Iterator`` must be a model of Bidirectional Traversal Iterator.  The
+type ``iterator_traits<Iterator>::reference`` must be the type of
+``*i``, where ``i`` is an object of type ``Iterator``.