diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py

index eff825dd22..3932599988 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -38,6 +38,7 @@ from synapse.metrics.background_process_metrics import wrap_as_background_proces
 from synapse.storage._base import SQLBaseStore, db_to_json, make_in_list_sql_clause
 from synapse.storage.database import (
     DatabasePool,
+    LoggingDatabaseConnection,
     LoggingTransaction,
     make_tuple_comparison_clause,
 )
@@ -61,7 +62,12 @@ BG_UPDATE_REMOVE_DUP_OUTBOUND_POKES = "remove_dup_outbound_pokes"
 
 
 class DeviceWorkerStore(SQLBaseStore):
-    def __init__(self, database: DatabasePool, db_conn, hs: "HomeServer"):
+    def __init__(
+        self,
+        database: DatabasePool,
+        db_conn: LoggingDatabaseConnection,
+        hs: "HomeServer",
+    ):
         super().__init__(database, db_conn, hs)
 
         if hs.config.worker.run_background_tasks:
@@ -953,7 +959,12 @@ class DeviceWorkerStore(SQLBaseStore):
 
 
 class DeviceBackgroundUpdateStore(SQLBaseStore):
-    def __init__(self, database: DatabasePool, db_conn, hs: "HomeServer"):
+    def __init__(
+        self,
+        database: DatabasePool,
+        db_conn: LoggingDatabaseConnection,
+        hs: "HomeServer",
+    ):
         super().__init__(database, db_conn, hs)
 
         self.db_pool.updates.register_background_index_update(
@@ -1085,7 +1096,12 @@ class DeviceBackgroundUpdateStore(SQLBaseStore):
 
 
 class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
-    def __init__(self, database: DatabasePool, db_conn, hs: "HomeServer"):
+    def __init__(
+        self,
+        database: DatabasePool,
+        db_conn: LoggingDatabaseConnection,
+        hs: "HomeServer",
+    ):
         super().__init__(database, db_conn, hs)
 
         # Map of (user_id, device_id) -> bool. If there is an entry that implies