diff --git a/roles/docker/files/configs/matrix/homeserver.yaml b/roles/docker/files/configs/matrix/homeserver.yaml
index b9c2abf..3a4eca4 100644
--- a/roles/docker/files/configs/matrix/homeserver.yaml
+++ b/roles/docker/files/configs/matrix/homeserver.yaml
@@ -54,6 +54,10 @@ soft_file_limit: 0
 # Set to false to disable presence tracking on this homeserver.
 use_presence: true
 
+# If set to 'false', forbids any other homeserver to fetch the server's public
+# rooms directory via federation.
+allow_public_rooms_over_federation: true
+
 # The GC threshold parameters to pass to `gc.set_threshold`, if defined
 #
 #gc_thresholds: [700, 10, 10]