diff --git a/boards/models/thread.py b/boards/models/thread.py
--- a/boards/models/thread.py
+++ b/boards/models/thread.py
@@ -282,6 +282,7 @@ class Thread(models.Model):
     def get_reply_tree(self):
         replies = self.get_replies().prefetch_related('refposts')
         tree = []
+        parent_positions = {}
         for reply in replies:
             parents = reply.refposts.all()
             found_parent = False
@@ -290,8 +291,11 @@ class Thread(models.Model):
                 for depth, element in tree:
                     index += 1
                     if element in parents:
-                        tree.insert(index, (depth + 1, reply))
+                        offset_under_parent = parent_positions.get(element, 1)
+                        tree.insert(index + offset_under_parent - 1, (depth + 1, reply))
+                        parent_positions[element] = offset_under_parent + 1
                         found_parent = True
+
             if not found_parent:
                 tree.append((0, reply))