diff --git a/mmocr/utils/ocr.py b/mmocr/utils/ocr.py
index 1c5f342e..5631b1ad 100755
--- a/mmocr/utils/ocr.py
+++ b/mmocr/utils/ocr.py
@@ -411,7 +411,7 @@ class MMOCR:
                  merge=False,
                  merge_xdist=20,
                  **kwargs):
-        args = locals()
+        args = locals().copy()
         [args.pop(x, None) for x in ['kwargs', 'self']]
         args = Namespace(**args)