diff --git a/backend/fluksio/flow/controller.py b/backend/fluksio/flow/controller.py
index e05d8d9..1ffce99 100644
--- a/backend/fluksio/flow/controller.py
+++ b/backend/fluksio/flow/controller.py
@@ -916,12 +916,12 @@ class FlowController:
         placer, pool = self.placer, self.workers
 
         def call(**kwargs: Any) -> Any:
-            with placer.claim(
+            with placer.claim(  # type: ignore[union-attr]
                 wanted, device=device, policy=policy, node=node_id, run=run_id
             ) as (target, allocation):
                 env = derive_env(wanted, allocation)
                 if target.worker is None:
-                    return pool.for_env(env).run(
+                    return pool.for_env(env).run(  # type: ignore[union-attr]
                         owner,
                         local,
                         code,