diff --git a/weave/trace_server/clickhouse_trace_server_batched.py b/weave/trace_server/clickhouse_trace_server_batched.py
index 5d4a87f61ed..ce31704caaf 100644
--- a/weave/trace_server/clickhouse_trace_server_batched.py
+++ b/weave/trace_server/clickhouse_trace_server_batched.py
@@ -927,7 +927,7 @@ def get_object_refs_root_val(
         ) -> Any:
             conds: list[str] = []
             object_id_conds: list[str] = []
-            parameters: dict[str, str | int] = {}
+            parameters: dict[str, Union[str, int]] = {}
 
             for ref_index, ref in enumerate(refs):
                 if ref.version == "latest":