diff --git a/extra/modules/root.py b/extra/modules/root.py
index 3510631..858a737 100644
--- a/extra/modules/root.py
+++ b/extra/modules/root.py
@@ -851,9 +851,12 @@ class AlternateRootDirectory(OldRootDirectory):
         except KeyError:
             pass
         else:
-            if formdef.category_id is None:
+            # if there's no category, or the request is a POST, directly call
+            # into FormsRootDirectory.
+            if formdef.category_id is None or get_request().get_method() == 'POST':
                 get_response().filter['bigdiv'] = 'rub_service'
                 return FormsRootDirectory()._q_lookup(component)
+
             # if there is category, let it fall back to raise TraversalError,
             # it will get caught in _q_traverse that will redirect it to an
             # URL embedding the category