diff --git a/stdlib/2and3/contextlib.pyi b/stdlib/2and3/contextlib.pyi
index 948fcff7a..ab1150140 100644
--- a/stdlib/2and3/contextlib.pyi
+++ b/stdlib/2and3/contextlib.pyi
@@ -51,11 +51,11 @@ if sys.version_info >= (3, 4):
                      exctb: Optional[TracebackType]) -> bool: ...
 
     class redirect_stdout(ContextManager[None]):
-        def __init__(self, new_target: IO[str]) -> None: ...
+        def __init__(self, new_target: Optional[IO[str]]) -> None: ...
 
 if sys.version_info >= (3, 5):
     class redirect_stderr(ContextManager[None]):
-        def __init__(self, new_target: IO[str]) -> None: ...
+        def __init__(self, new_target: Optional[IO[str]]) -> None: ...
 
 if sys.version_info >= (3,):
     class ContextDecorator: