diff --git a/faust/streams.py b/faust/streams.py
index 7237be684..7b12f42b5 100644
--- a/faust/streams.py
+++ b/faust/streams.py
@@ -843,7 +843,7 @@ async def _py_aiter(self) -> AsyncIterator:
                 # wait for next message
                 value: Any = None
                 # we iterate until on_merge gives value.
-                while value is None:
+                while value is None and event is None:
                     await sleep(0, loop=loop)
                     # get message from channel
                     # This inlines ThrowableQueue.get for performance: