diff --git a/api/onnx_web/chain/source_s3.py b/api/onnx_web/chain/source_s3.py
index 6e2df551..a35480ad 100644
--- a/api/onnx_web/chain/source_s3.py
+++ b/api/onnx_web/chain/source_s3.py
@@ -6,8 +6,8 @@ from boto3 import Session
 from PIL import Image
 
 from ..params import ImageParams, StageParams
-from ..server import ProgressCallback, ServerContext
-from ..worker import WorkerContext
+from ..server import ServerContext
+from ..worker import WorkerContext, ProgressCallback
 from .base import BaseStage
 from .result import ImageMetadata, StageResult