diff --git a/app/models/site.rb b/app/models/site.rb
index 1c62e9b..3a69923 100644
--- a/app/models/site.rb
+++ b/app/models/site.rb
@@ -390,7 +390,7 @@ class Site < ApplicationRecord
 
   # Detecta si el tema actual es una gema
   def theme_available?
-    available_themes.include? design.gem
+    available_themes.include? design&.gem
   end
 
   # Devuelve el dominio actual