diff --git a/synapse/handlers/sliding_sync.py b/synapse/handlers/sliding_sync.py
index 6071f9d868..622a16f31c 100644
--- a/synapse/handlers/sliding_sync.py
+++ b/synapse/handlers/sliding_sync.py
@@ -185,6 +185,7 @@ class SlidingSyncHandler:
         pass
 
     async def current_sync_for_user(
+        self,
         sync_config: SlidingSyncConfig,
         from_token: Optional[StreamToken] = None,
         to_token: Optional[StreamToken] = None,
diff --git a/synapse/rest/client/sync.py b/synapse/rest/client/sync.py
index d6ff731584..fda5892cda 100644
--- a/synapse/rest/client/sync.py
+++ b/synapse/rest/client/sync.py
@@ -739,7 +739,9 @@ class SlidingSyncRestServlet(RestServlet):
         sync_config = SlidingSyncConfig(
             user=user,
             device_id=device_id,
-            # TODO: Copy SlidingSyncBody fields into SlidingSyncConfig
+            lists=body.lists,
+            room_subscriptions=body.room_subscriptions,
+            extensions=body.extensions,
         )
 
         sliding_sync_results = await self.sliding_sync_handler.wait_for_sync_for_user(