diff --git a/mmdet/datasets/transforms/transforms.py b/mmdet/datasets/transforms/transforms.py
index 4ac2bf75b54..c50b987db33 100644
--- a/mmdet/datasets/transforms/transforms.py
+++ b/mmdet/datasets/transforms/transforms.py
@@ -1766,8 +1766,10 @@ def _postprocess_results(
                     results['masks'] = np.array(
                         [results['masks'][i] for i in results['idx_mapper']])
                     results['masks'] = ori_masks.__class__(
-                        results['masks'], ori_masks.height, ori_masks.width)
-
+                        results['masks'],
+                        results['masks'][0].shape[0],
+                        results['masks'][0].shape[1],
+                    )
                 if (not len(results['idx_mapper'])
                         and self.skip_img_without_anno):
                     return None