diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index 69d2c8c36..f06914a37 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -209,9 +209,7 @@ class AdminHandler(BaseHandler):
                     # Now check if this event is an unseen prev event, if so
                     # then we remove this event from the appropriate dicts.
                     for child_id in unseen_to_child_events.pop(event.event_id, []):
-                        event_to_unseen_prevs.get(child_id, set()).discard(
-                            event.event_id
-                        )
+                        event_to_unseen_prevs[child_id].discard(event.event_id)
 
                     written_events.add(event.event_id)
 
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index d9482a384..7b5b3b8c8 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -833,7 +833,9 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         Returns:
             Deferred[tuple[list[_EventDictReturn], str]]: Returns the results
             as a list of _EventDictReturn and a token that points to the end
-            of the result set.
+            of the result set. If no events are returned then the end of the
+            stream has been reached (i.e. there are no events between
+            `from_token` and `to_token`).
         """
 
         assert int(limit) >= 0
@@ -905,15 +907,17 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
                 only those before
             direction(char): Either 'b' or 'f' to indicate whether we are
                 paginating forwards or backwards from `from_key`.
-            limit (int): The maximum number of events to return. Zero or less
-                means no limit.
+            limit (int): The maximum number of events to return.
             event_filter (Filter|None): If provided filters the events to
                 those that match the filter.
 
         Returns:
-            tuple[list[dict], str]: Returns the results as a list of dicts and
-            a token that points to the end of the result set. The dicts have
-            the keys "event_id", "topological_ordering" and "stream_orderign".
+            tuple[list[FrozenEvents], str]: Returns the results as a list of
+            dicts and a token that points to the end of the result set. The
+            dicts have the keys "event_id", "topological_ordering" and
+            "stream_ordering". If no events are returned then the end of the
+            stream has been reached (i.e. there are no events between
+            `from_key` and `to_key`).
         """
 
         from_key = RoomStreamToken.parse(from_key)