1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/storage/data_stores/main/devices.py b/synapse/storage/data_stores/main/devices.py
index 343cf9a2d5..45581a6500 100644
--- a/synapse/storage/data_stores/main/devices.py
+++ b/synapse/storage/data_stores/main/devices.py
@@ -577,7 +577,7 @@ class DeviceWorkerStore(SQLBaseStore):
             rows = yield self.db.execute(
                 "get_users_whose_signatures_changed", None, sql, user_id, from_key
             )
-            return {user for row in rows for user in json.loads(row[0])}
+            return {user for row in rows for user in db_to_json(row[0])}
         else:
             return set()