diff --git a/synapse/replication/slave/storage/devices.py b/synapse/replication/slave/storage/devices.py
index d9300fce33..f045e1b937 100644
--- a/synapse/replication/slave/storage/devices.py
+++ b/synapse/replication/slave/storage/devices.py
@@ -33,6 +33,9 @@ class SlavedDeviceStore(EndToEndKeyWorkerStore, DeviceWorkerStore, BaseSlavedSto
         self._device_list_stream_cache = StreamChangeCache(
             "DeviceListStreamChangeCache", device_list_max
         )
+        self._user_signature_stream_cache = StreamChangeCache(
+            "UserSignatureStreamChangeCache", device_list_max
+        )
         self._device_list_federation_stream_cache = StreamChangeCache(
             "DeviceListFederationStreamChangeCache", device_list_max
         )