diff --git a/temporalio/client.py b/temporalio/client.py
index e9ecefe62..1d66d2550 100644
--- a/temporalio/client.py
+++ b/temporalio/client.py
@@ -2020,6 +2020,7 @@ async def _start_update(
             StartWorkflowUpdateInput(
                 id=self._id,
                 run_id=self._run_id,
+                first_execution_run_id=self.first_execution_run_id,
                 update_id=id,
                 update=update_name,
                 args=temporalio.common._arg_or_args(arg, args),
@@ -4648,6 +4649,7 @@ class StartWorkflowUpdateInput:
 
     id: str
     run_id: Optional[str]
+    first_execution_run_id: Optional[str]
     update_id: Optional[str]
     update: str
     args: Sequence[Any]
@@ -5275,6 +5277,7 @@ async def start_workflow_update(
                 workflow_id=input.id,
                 run_id=input.run_id or "",
             ),
+            first_execution_run_id=input.first_execution_run_id or "",
             request=temporalio.api.update.v1.Request(
                 meta=temporalio.api.update.v1.Meta(
                     update_id=input.update_id or str(uuid.uuid4()),