diff --git a/pep-0492.txt b/pep-0492.txt
index 0ce52a678..ec627abd4 100644
--- a/pep-0492.txt
+++ b/pep-0492.txt
@@ -152,6 +152,9 @@ can be one of:
   and would be like using ``__iter__`` instead of ``__call__`` for
   regular callables.
 
+  It is a ``TypeError`` if ``__await__`` returns anything but an
+  iterator.
+
 It is a ``SyntaxError`` to use ``await`` outside of a coroutine.