diff --git a/README.md b/README.md
index 1ccdc835..a724328d 100644
--- a/README.md
+++ b/README.md
@@ -1226,7 +1226,7 @@ class LabDoor implements Door
 ```
 Then we have a proxy to secure any doors that we want
 ```php
-class SecuredDoor
+class SecuredDoor implements Door
 {
     protected $door;