1 files changed, 4 insertions, 0 deletions
diff --git a/synapse/rest/client/sync.py b/synapse/rest/client/sync.py
index c2989765ce..f1c23d68e5 100644
--- a/synapse/rest/client/sync.py
+++ b/synapse/rest/client/sync.py
@@ -509,6 +509,10 @@ class SyncRestServlet(RestServlet):
             ephemeral_events = room.ephemeral
             result["ephemeral"] = {"events": ephemeral_events}
             result["unread_notifications"] = room.unread_notifications
+            if room.unread_thread_notifications:
+                result[
+                    "org.matrix.msc3773.unread_thread_notifications"
+                ] = room.unread_thread_notifications
             result["summary"] = room.summary
             if self._msc2654_enabled:
                 result["org.matrix.msc2654.unread_count"] = room.unread_count