diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index b94c26a1ae8c56a0260fc64ab6441efb8c0fb628..922bbb4f737936b790dbc3ab50e0fcdb57639564 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -294,7 +294,7 @@ Getting closer... Now we will implement the code of the `acts_as_yaffle` method
 
 module Yaffle
   module ActsAsYaffle
-   extend ActiveSupport::Concern
+    extend ActiveSupport::Concern
 
     included do
     end