diff --git a/docs/examples/models_recursive.py b/docs/examples/models_recursive.py
index <HASH>..<HASH> 100644
--- a/docs/examples/models_recursive.py
+++ b/docs/examples/models_recursive.py
@@ -1,10 +1,10 @@
-from typing import List
+from typing import List, Optional
 from pydantic import BaseModel
 
 
 class Foo(BaseModel):
     count: int
-    size: float = None
+    size: Optional[float] = None
 
 
 class Bar(BaseModel):
Fix mypy error in models_recursive.py example. (#<I>)