diff --git a/boards/models/source.py b/boards/models/source.py
--- a/boards/models/source.py
+++ b/boards/models/source.py
@@ -1,5 +1,6 @@
 import feedparser
 import logging
+import calendar
 
 from time import mktime
 from datetime import datetime
@@ -51,7 +52,7 @@ class ThreadSource(models.Model):
                 items = sorted(feed.entries, key=lambda entry: entry.published_parsed)
                 for item in items:
                     title = item.title[:TITLE_MAX_LENGTH]
-                    timestamp = datetime.fromtimestamp(mktime(item.published_parsed), tz=utc)
+                    timestamp = datetime.fromtimestamp(calendar.timegm(item.published_parsed), tz=utc)
                     if not timestamp:
                         logger.error('Invalid timestamp {} for {}'.format(item.published, title))
                     else: