diff --git a/ppdet/modeling/architectures/yolov3.py b/ppdet/modeling/architectures/yolov3.py
index 4f2a35db31d496f5ab9f414bcba88069e6514f1d..cff0dec6df58dad0e7ca9f3e4991bb5fb4d99309 100644
--- a/ppdet/modeling/architectures/yolov3.py
+++ b/ppdet/modeling/architectures/yolov3.py
@@ -121,7 +121,7 @@ class YOLOv3(object):
                     -2] // downsample if image_shape[-2] else None
                 targets_def[k]['shape'][4] = image_shape[
                     -1] // downsample if image_shape[-1] else None
-                downsample // 2
+                downsample //= 2
 
             inputs_def.update(targets_def)