diff --git a/src/main/asciidoc/object-mapping.adoc b/src/main/asciidoc/object-mapping.adoc
index 0db581487..79d2135df 100644
--- a/src/main/asciidoc/object-mapping.adoc
+++ b/src/main/asciidoc/object-mapping.adoc
@@ -181,7 +181,7 @@ class Person {
   }
 
   Person withId(Long id) {                                                  <1>
-    return new Person(id, this.firstname, this.lastname, this.birthday);
+    return new Person(id, this.firstname, this.lastname, this.birthday, this.age);
   }
 
   void setRemarks(String remarks) {                                         <5>