1 files changed, 2 insertions, 0 deletions
diff --git a/synapse/storage/stats.py b/synapse/storage/stats.py
index c2f11b84bd..5dab6089ff 100644
--- a/synapse/storage/stats.py
+++ b/synapse/storage/stats.py
@@ -15,10 +15,12 @@
 # limitations under the License.
 
 import logging
+from itertools import chain
 from threading import Lock
 
 from twisted.internet import defer
 
+from synapse.storage.engines import Sqlite3Engine
 from synapse.storage.state_deltas import StateDeltasStore
 from synapse.util.caches.descriptors import cached