diff --git a/tildes/tildes/models/comment/comment.py b/tildes/tildes/models/comment/comment.py
index b8788a7..e1a4063 100644
--- a/tildes/tildes/models/comment/comment.py
+++ b/tildes/tildes/models/comment/comment.py
@@ -170,7 +170,8 @@ class Comment(DatabaseModel):
             acl.append((Allow, 'admin', 'view'))
 
             acl.append((Allow, self.user_id, 'view'))
-            acl.append((Allow, self.user_id, 'reply'))
+            if not self.topic.is_locked:
+                acl.append((Allow, self.user_id, 'reply'))
             acl.append((Allow, self.user_id, 'edit'))
             acl.append((Allow, self.user_id, 'delete'))