diff --git a/ruby_oop_design.md b/ruby_oop_design.md
index c3cc5b2..a1c7419 100644
--- a/ruby_oop_design.md
+++ b/ruby_oop_design.md
@@ -473,7 +473,7 @@ module Foo
   SomeConstant = 'hello'
 end
 
-Bar.constants # => [:SomeConstant]
+Foo.constants # => [:SomeConstant]
 ```
 
 To find the path of a specific module, the `Module.nesting` can be used: