diff --git a/ppdet/engine/__init__.py b/ppdet/engine/__init__.py
index 5e05ae637480508ea51c5c6a7cabd64e3feaa9d2..9d14ee6344a029cd0acfb0522c1ca7fbf7b85357 100644
--- a/ppdet/engine/__init__.py
+++ b/ppdet/engine/__init__.py
@@ -27,4 +27,4 @@ __all__ = trainer.__all__ \
 
 from . import tracker
 from .tracker import *
-__all__ = __all__ + tracker.__all__ \
+__all__ = __all__ + tracker.__all__