diff --git a/radicale/__init__.py b/radicale/__init__.py
index 692e633..9d606f6 100644
--- a/radicale/__init__.py
+++ b/radicale/__init__.py
@@ -340,7 +340,7 @@ class Application(object):
                user):
         """Manage DELETE request."""
         if not len(write_collections):
-            return client.PRECONDITION_FAILED, {}, None
+            return return NOT_ALLOWED
 
         collection = write_collections[0]