diff --git a/boards/views/__init__.py b/boards/views/__init__.py
--- a/boards/views/__init__.py
+++ b/boards/views/__init__.py
@@ -211,6 +211,11 @@ def thread(request, post_id, mode=MODE_N
         kwargs = {}
 
     opening_post = get_object_or_404(Post, id=post_id)
+
+    # If this is not OP, don't show it as it is
+    if not opening_post.is_opening():
+        raise Http404
+
     if request.method == 'POST' and not opening_post.thread_new.archived:
         form = postFormClass(request.POST, request.FILES,
                              error_class=PlainErrorList, **kwargs)