diff --git a/app/models/user.rb b/app/models/user.rb
index 9e95c50bf8f..c2a8ece8963 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -491,8 +491,8 @@ class User < ActiveRecord::Base
   end
 
   def secure_category_ids
-    cats = self.staff? ? Category.select(:id).where(read_restricted: true) : secure_categories.select('categories.id').references(:categories)
-    cats.map { |c| c.id }.sort
+    cats = self.staff? ? Category.where(read_restricted: true) : secure_categories.references(:categories)
+    cats.pluck('categories.id').sort
   end
 
   def topic_create_allowed_category_ids