diff --git a/boards/migrations/0025_auto_20150825_2049.py b/boards/migrations/0025_auto_20150825_2049.py
--- a/boards/migrations/0025_auto_20150825_2049.py
+++ b/boards/migrations/0025_auto_20150825_2049.py
@@ -2,14 +2,21 @@
 from __future__ import unicode_literals
 
 from django.db import migrations
-from boards.models import Post
 
 
 class Migration(migrations.Migration):
 
-    def refuild_refmap(apps, schema_editor):
+    def rebuild_refmap(apps, schema_editor):
+        Post = apps.get_model('boards', 'Post')
         for post in Post.objects.all():
-            post.build_refmap()
+            refposts = list()
+            for refpost in post.referenced_posts.all():
+                result = '<a href="{}">&gt;&gt;{}</a>'.format(refpost.get_absolute_url(),
+                        self.id)
+                if refpost.is_opening():
+                    result = '<b>{}</b>'.format(result)
+                refposts += result
+            post.refmap = ', '.join(refposts)
             post.save(update_fields=['refmap'])
 
     dependencies = [
@@ -17,5 +24,5 @@ class Migration(migrations.Migration):
     ]
 
     operations = [
-        migrations.RunPython(refuild_refmap),
+        migrations.RunPython(rebuild_refmap),
     ]
diff --git a/boards/models/thread.py b/boards/models/thread.py
--- a/boards/models/thread.py
+++ b/boards/models/thread.py
@@ -72,8 +72,9 @@ class ThreadManager(models.Manager):
                 new_post_count=Count('multi_replies'))
 
     def get_new_post_count(self, datas):
-        return self.get_new_posts(datas).aggregate(
-            total_count=Count('multi_replies'))['total_count']
+        new_posts = self.get_new_posts(datas)
+        return new_posts.aggregate(total_count=Count('multi_replies'))\
+                ['total_count'] if new_posts else 0
 
 
 def get_thread_max_posts():
@@ -224,7 +225,7 @@ class Thread(models.Model):
     def update_posts_time(self, exclude_posts=None):
         last_edit_time = self.last_edit_time
 
-        for post in self.post_set.all():
+        for post in self.multi_replies.all():
             if exclude_posts is None or post not in exclude_posts:
                 # Manual update is required because uids are generated on save
                 post.last_edit_time = last_edit_time