diff --git a/app/models/article.rb b/app/models/article.rb
index 86e0025..d00ad73 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -253,7 +253,7 @@ class Article < ActiveRecord::Base
 
   # retrieves all articles belonging to the given +profile+ that are not
   # sub-articles of any other article.
-  scope :top_level_for, -> {
+  scope :top_level_for, -> (profile) {
     where 'parent_id is null and profile_id = ?', profile.id
   }
 
--
libgit2 0.21.2