diff --git a/scrapy/pipelines/files.py b/scrapy/pipelines/files.py
index 250f46ad8..a449793c9 100644
--- a/scrapy/pipelines/files.py
+++ b/scrapy/pipelines/files.py
@@ -7,9 +7,9 @@ See documentation in topics/media-pipeline.rst
 import hashlib
 import os
 import os.path
-import rfc822
 import time
 import logging
+from email.utils import parsedate_tz, mktime_tz
 from six.moves.urllib.parse import urlparse
 from collections import defaultdict
 import six
@@ -91,8 +91,8 @@ class S3FilesStore(object):
         def _onsuccess(boto_key):
             checksum = boto_key.etag.strip('"')
             last_modified = boto_key.last_modified
-            modified_tuple = rfc822.parsedate_tz(last_modified)
-            modified_stamp = int(rfc822.mktime_tz(modified_tuple))
+            modified_tuple = parsedate_tz(last_modified)
+            modified_stamp = int(mktime_tz(modified_tuple))
             return {'checksum': checksum, 'last_modified': modified_stamp}
 
         return self._get_boto_key(path).addCallback(_onsuccess)
diff --git a/scrapy/utils/defer.py b/scrapy/utils/defer.py
index 7a3f20476..8f3824abf 100644
--- a/scrapy/utils/defer.py
+++ b/scrapy/utils/defer.py
@@ -97,7 +97,7 @@ def iter_errback(iterable, errback, *a, **kw):
     iterating it.
     """
     it = iter(iterable)
-    while 1:
+    while True:
         try:
             yield next(it)
         except StopIteration:
diff --git a/scrapy/utils/misc.py b/scrapy/utils/misc.py
index c269b7f74..4215e41d2 100644
--- a/scrapy/utils/misc.py
+++ b/scrapy/utils/misc.py
@@ -106,7 +106,7 @@ def md5sum(file):
     '784406af91dd5a54fbb9c84c2236595a'
     """
     m = hashlib.md5()
-    while 1:
+    while True:
         d = file.read(8096)
         if not d:
             break