diff --git a/apps/reader/models.py b/apps/reader/models.py
index 529630fad..588276715 100644
--- a/apps/reader/models.py
+++ b/apps/reader/models.py
@@ -189,13 +189,13 @@ class MUserStory(mongo.Document):
     
     meta = {
         'collection': 'userstories',
-        'indexes': [('user_id', 'feed_id')],
+        'indexes': ['feed_id', ('user_id', 'feed_id')],
         'allow_inheritance': False,
     }
     
     @classmethod
-    def delete_old_stories(cls):
-        MUserStory.objects(read_date__lte=UNREAD_CUTOFF).delete()
+    def delete_old_stories(cls, feed_id):
+        MUserStory.objects(feed_id=feed_id, read_date__lte=UNREAD_CUTOFF).delete()
     
         
 class UserSubscriptionFolders(models.Model):
diff --git a/utils/feed_fetcher.py b/utils/feed_fetcher.py
index 3c5256a9b..a843169a0 100644
--- a/utils/feed_fetcher.py
+++ b/utils/feed_fetcher.py
@@ -314,7 +314,7 @@ class Dispatcher:
                         if not feed.fetched_once:
                             feed.fetched_once = True
                             feed.save()
-                        MUserStory.delete_old_stories()
+                        MUserStory.delete_old_stories(feed_id=feed.pk)
                         user_subs = UserSubscription.objects.filter(feed=feed)
                         logging.debug(u'   ---> [%-30s] Computing scores for all feed subscribers: %s subscribers' % (unicode(feed)[:30], user_subs.count()))
                         stories_db = MStory.objects(story_feed_id=feed.pk,