diff --git a/boards/views.py b/boards/views.py
--- a/boards/views.py
+++ b/boards/views.py
@@ -429,7 +429,9 @@ def api_get_threaddiff(request, thread_i
         'updated': [],
         'last_update': None,
     }
-    added_posts = Post.objects.filter(thread=thread, pub_time__gt=filter_time)
+    added_posts = Post.objects.filter(thread=thread,
+                                      pub_time__gt=filter_time)\
+        .order_by('pub_time')
     updated_posts = Post.objects.filter(thread=thread,
                                         pub_time__lt=filter_time,
                                         last_edit_time__gt=filter_time)