diff --git a/docs/validate.rst b/docs/validate.rst
index 24e7389d6..f447f761d 100644
--- a/docs/validate.rst
+++ b/docs/validate.rst
@@ -213,7 +213,7 @@ existing `TypeChecker` or create a new one. You may then create a new
 
     def is_my_int(checker, instance):
         return (
-            checker.is_type(instance, "number") or
+            Draft3Validator.TYPE_CHECKER.is_type(instance, "number") or
             isinstance(instance, MyInteger)
         )