diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 3dbedb2c4..c0205da1a 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -832,8 +832,8 @@ class SyncHandler(object):
 
     @defer.inlineCallbacks
     def _have_rooms_changed(self, sync_result_builder):
-        """Returns whether any rooms have changed since the sync. Must be an
-        incremental sync
+        """Returns whether there may be any new events that should be sent down
+        the sync. Returns True if there are.
         """
         user_id = sync_result_builder.sync_config.user.to_string()
         since_token = sync_result_builder.since_token
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 5f044a3f1..e38d8927b 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -276,6 +276,8 @@ class RoomMemberStore(SQLBaseStore):
 
     @cachedInlineCallbacks(max_entries=500000, iterable=True)
     def get_rooms_for_user(self, user_id):
+        """Returns a set of room_ids the user is currently joined to
+        """
         rooms = yield self.get_rooms_for_user_where_membership_is(
             user_id, membership_list=[Membership.JOIN],
         )