diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index d83b58adb9..bec53e6a4c 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1536,11 +1536,15 @@ class SyncHandler:
             await_full_state=await_full_state,
         )
 
-        state_at_previous_sync_start = {} if since_token.prev_batch is None else await self._state_storage_controller.get_state_ids_at(
-            room_id,
-            stream_position=since_token.prev_batch,
-            state_filter=state_filter,
-            await_full_state=await_full_state,
+        state_at_previous_sync_start = (
+            {}
+            if since_token.prev_batch is None
+            else await self._state_storage_controller.get_state_ids_at(
+                room_id,
+                stream_position=since_token.prev_batch,
+                state_filter=state_filter,
+                await_full_state=await_full_state,
+            )
         )
 
         state_at_timeline_end = await self._state_storage_controller.get_state_ids_at(
diff --git a/synapse/types/__init__.py b/synapse/types/__init__.py
index 454da2b815..531aa29d9d 100644
--- a/synapse/types/__init__.py
+++ b/synapse/types/__init__.py
@@ -988,7 +988,9 @@ class StreamToken:
 
     @classmethod
     @cancellable
-    async def from_string(cls, store: "DataStore", string: str, prev_batch: Optional["StreamToken"] = None) -> "StreamToken":
+    async def from_string(
+        cls, store: "DataStore", string: str, prev_batch: Optional["StreamToken"] = None
+    ) -> "StreamToken":
         """
         Creates a RoomStreamToken from its textual representation.
         """
@@ -997,7 +999,9 @@ class StreamToken:
                 # We have a prev_token
                 batches = string.split(cls._BATCH_SEPARATOR)
                 prev_batch = await StreamToken.from_string(store, batches[1])
-                batch = await StreamToken.from_string(store, batches[0], prev_batch=prev_batch)
+                batch = await StreamToken.from_string(
+                    store, batches[0], prev_batch=prev_batch
+                )
                 return batch
 
             keys = string.split(cls._SEPARATOR)
@@ -1036,12 +1040,16 @@ class StreamToken:
         except Exception:
             raise SynapseError(400, "Invalid stream token")
 
-    async def to_string(self, store: "DataStore", include_prev_batch: bool = True) -> str:
+    async def to_string(
+        self, store: "DataStore", include_prev_batch: bool = True
+    ) -> str:
         if include_prev_batch and self.prev_batch:
-            return self._BATCH_SEPARATOR.join([
-                await self.to_string(store, include_prev_batch=False),
-                await self.prev_batch.to_string(store, include_prev_batch=False),
-            ])
+            return self._BATCH_SEPARATOR.join(
+                [
+                    await self.to_string(store, include_prev_batch=False),
+                    await self.prev_batch.to_string(store, include_prev_batch=False),
+                ]
+            )
         else:
             return self._SEPARATOR.join(
                 [