diff --git a/stdlib/http/cookiejar.pyi b/stdlib/http/cookiejar.pyi
index faac20d13..56097f163 100644
--- a/stdlib/http/cookiejar.pyi
+++ b/stdlib/http/cookiejar.pyi
@@ -42,7 +42,7 @@ class CookieJar(Iterable[Cookie]):
     def __len__(self) -> int: ...
 
 class FileCookieJar(CookieJar):
-    filename: str
+    filename: str | None
     delayload: bool
     def __init__(self, filename: StrPath | None = None, delayload: bool = False, policy: CookiePolicy | None = None) -> None: ...
     def save(self, filename: str | None = None, ignore_discard: bool = False, ignore_expires: bool = False) -> None: ...