diff --git a/doc/sample/Person.im b/doc/sample/Person.im
index 3639ec9..83d0ff8 100755
--- a/doc/sample/Person.im
+++ b/doc/sample/Person.im
@@ -87,9 +87,9 @@ class Person
 
     - getAgeInUnit:units
         ^match units in
-            #years  => age,
-            #months => age / 12,
-            #days   => age / 365,
+            #years  => self.age,
+            #months => self.age / 12,
+            #days   => self.age / 365,
             _       => 0,
         end
     end