diff --git a/python_module/megengine/data/dataset/vision/objects365.py b/python_module/megengine/data/dataset/vision/objects365.py
index 84556d89..7c1481ba 100644
--- a/python_module/megengine/data/dataset/vision/objects365.py
+++ b/python_module/megengine/data/dataset/vision/objects365.py
@@ -129,7 +129,7 @@ class Objects365(VisionDataset):
         img_info = self.imgs[img_id]
         return img_info
 
-    class_name = (
+    class_names = (
         "person",
         "sneakers",
         "chair",
diff --git a/python_module/megengine/data/dataset/vision/voc.py b/python_module/megengine/data/dataset/vision/voc.py
index 95f373be..42bf712d 100644
--- a/python_module/megengine/data/dataset/vision/voc.py
+++ b/python_module/megengine/data/dataset/vision/voc.py
@@ -93,7 +93,9 @@ class PascalVOC(VisionDataset):
             elif k == "boxes_category":
                 anno = self.parse_voc_xml(ET.parse(self.annotations[index]).getroot())
                 boxes_category = [obj["name"] for obj in anno["annotation"]["object"]]
-                boxes_category = [self.class_names.index(bc) for bc in boxes_category]
+                boxes_category = [
+                    self.class_names.index(bc) + 1 for bc in boxes_category
+                ]
                 boxes_category = np.array(boxes_category, dtype=np.int32)
                 target.append(boxes_category)
             elif k == "mask":