diff --git a/stubs/requests/requests/models.pyi b/stubs/requests/requests/models.pyi
index 5fc38b72e..d710de8e7 100644
--- a/stubs/requests/requests/models.pyi
+++ b/stubs/requests/requests/models.pyi
@@ -105,7 +105,7 @@ class PreparedRequest(RequestEncodingMixin, RequestHooksMixin):
     def prepare_url(self, url, params) -> None: ...
     def prepare_headers(self, headers) -> None: ...
     def prepare_body(self, data, files, json=None) -> None: ...
-    def prepare_content_length(self, body) -> None: ...
+    def prepare_content_length(self, body: bytes | str | None) -> None: ...
     def prepare_auth(self, auth, url="") -> None: ...
     def prepare_cookies(self, cookies) -> None: ...
     def prepare_hooks(self, hooks) -> None: ...