diff --git a/synapse/types/handlers/__init__.py b/synapse/types/handlers/__init__.py
index 1ba5ea55c1..8e097d8b48 100644
--- a/synapse/types/handlers/__init__.py
+++ b/synapse/types/handlers/__init__.py
@@ -31,10 +31,12 @@ else:
     from pydantic import Extra
 
 from synapse.events import EventBase
-from synapse.handlers.relations import BundledAggregations
 from synapse.types import JsonDict, JsonMapping, StreamToken, UserID
 from synapse.types.rest.client import SlidingSyncBody
 
+if TYPE_CHECKING:
+    from synapse.handlers.relations import BundledAggregations
+
 
 class ShutdownRoomParams(TypedDict):
     """
@@ -197,7 +199,7 @@ class SlidingSyncResult:
         initial: bool
         required_state: List[EventBase]
         timeline_events: List[EventBase]
-        bundled_aggregations: Optional[Dict[str, BundledAggregations]]
+        bundled_aggregations: Optional[Dict[str, "BundledAggregations"]]
         is_dm: bool
         stripped_state: Optional[List[JsonDict]]
         prev_batch: StreamToken