diff --git a/verl/single_controller/ray/base.py b/verl/single_controller/ray/base.py
index ce607bbf612..0ec0c97e623 100644
--- a/verl/single_controller/ray/base.py
+++ b/verl/single_controller/ray/base.py
@@ -406,7 +406,7 @@ def worker_names(self):
     @classmethod
     def from_detached(
         cls,
-        name_prefix,
+        name_prefix=None,
         worker_names=None,
         worker_handles=None,
         ray_cls_with_init=None,