diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index fed7262be245..51d4cdcb2a5e 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -761,5 +761,5 @@ def invalidate_local(self, key: KT) -> None:
     async def contains(self, key: KT) -> bool:
         return self._lru_cache.contains(key)
 
-    def clear(self) -> None:
+    async def clear(self) -> None:
         self._lru_cache.clear()
diff --git a/tests/handlers/test_sync.py b/tests/handlers/test_sync.py
index ecc7cc6461ee..e3f38fbcc5ce 100644
--- a/tests/handlers/test_sync.py
+++ b/tests/handlers/test_sync.py
@@ -159,7 +159,7 @@ def test_unknown_room_version(self):
 
         # Blow away caches (supported room versions can only change due to a restart).
         self.store.get_rooms_for_user_with_stream_ordering.invalidate_all()
-        self.store._get_event_cache.clear()
+        self.get_success(self.store._get_event_cache.clear())
         self.store._event_ref.clear()
 
         # The rooms should be excluded from the sync response.
diff --git a/tests/storage/databases/main/test_events_worker.py b/tests/storage/databases/main/test_events_worker.py
index 38963ce4a74c..46d829b062a0 100644
--- a/tests/storage/databases/main/test_events_worker.py
+++ b/tests/storage/databases/main/test_events_worker.py
@@ -143,7 +143,7 @@ def prepare(self, reactor, clock, hs):
         self.event_id = res["event_id"]
 
         # Reset the event cache so the tests start with it empty
-        self.store._get_event_cache.clear()
+        self.get_success(self.store._get_event_cache.clear())
 
     def test_simple(self):
         """Test that we cache events that we pull from the DB."""
@@ -160,7 +160,7 @@ def test_event_ref(self):
         """
 
         # Reset the event cache
-        self.store._get_event_cache.clear()
+        self.get_success(self.store._get_event_cache.clear())
 
         with LoggingContext("test") as ctx:
             # We keep hold of the event event though we never use it.
@@ -170,7 +170,7 @@ def test_event_ref(self):
             self.assertEqual(ctx.get_resource_usage().evt_db_fetch_count, 1)
 
         # Reset the event cache
-        self.store._get_event_cache.clear()
+        self.get_success(self.store._get_event_cache.clear())
 
         with LoggingContext("test") as ctx:
             self.get_success(self.store.get_event(self.event_id))
@@ -345,7 +345,7 @@ def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer):
         self.event_id = res["event_id"]
 
         # Reset the event cache so the tests start with it empty
-        self.store._get_event_cache.clear()
+        self.get_success(self.store._get_event_cache.clear())
 
     @contextmanager
     def blocking_get_event_calls(