diff --git a/api/client-server/definitions/room_event_filter.yaml b/api/client-server/definitions/room_event_filter.yaml
index 628e2ca8..0ad1ae33 100644
--- a/api/client-server/definitions/room_event_filter.yaml
+++ b/api/client-server/definitions/room_event_filter.yaml
@@ -3,7 +3,7 @@ allOf:
 properties:
   not_rooms:
     description: A list of room IDs to exclude. If this list is absent then no rooms
-      are excluded. A matching room will be excluded even if it is listed in the 'rooms'
+      are excluded. A matching room will be excluded even if it is listed in the ``'rooms'``
       filter.
     items:
       type: string