diff --git a/external/mmdetection/detection_tasks/apis/detection/openvino_task.py b/external/mmdetection/detection_tasks/apis/detection/openvino_task.py
index c9c1dcd8f22..9ec75118924 100644
--- a/external/mmdetection/detection_tasks/apis/detection/openvino_task.py
+++ b/external/mmdetection/detection_tasks/apis/detection/openvino_task.py
@@ -135,7 +135,7 @@ def __init__(
         hparams: OTEDetectionConfig,
         label_schema: LabelSchemaEntity,
         model_file: Union[str, bytes],
-        weight_file: Optional[str, bytes] = None,
+        weight_file: Union[str, bytes, None] = None,
         device: str = "CPU",
         num_requests: int = 1,
     ):