diff --git a/active_bots/mastodonbot.py b/active_bots/mastodonbot.py
index 5127eab..adfac48 100755
--- a/active_bots/mastodonbot.py
+++ b/active_bots/mastodonbot.py
@@ -29,7 +29,7 @@ class MastodonBot(Bot):
             logger.error("Unknown Mastodon API Error.", exc_info=True)
             return mentions
         for status in notifications:
-            if user.get_seen_toot() == None:
+            if user.get_seen_toot() is None:
                 user.init_seen_toot(m.instance()['uri'])
             if (status['type'] == 'mention' and
                     status['status']['id'] > user.get_seen_toot()):