diff --git a/readme.md b/readme.md
index b9c8c571f..02808b7de 100644
--- a/readme.md
+++ b/readme.md
@@ -754,7 +754,7 @@ Progress events for uploading (sending a request) and downloading (receiving a r
 }
 ```
 
-If it's not possible to retrieve the body size (can happen when streaming), `total` will be `null`.
+If it's not possible to retrieve the body size (can happen when streaming), `total` will be `undefined`.
 
 ```js
 (async () => {