diff --git a/scrapy/http/headers.py b/scrapy/http/headers.py
index a9471d721..9c03fe54f 100644
--- a/scrapy/http/headers.py
+++ b/scrapy/http/headers.py
@@ -1,7 +1,8 @@
+from collections.abc import Mapping
+
 from w3lib.http import headers_dict_to_raw
 from scrapy.utils.datatypes import CaselessDict
 from scrapy.utils.python import to_unicode
-from collections.abc import Mapping
 
 
 class Headers(CaselessDict):