diff --git a/httpx/_client.py b/httpx/_client.py
index 9a759deaee..d2ce666890 100644
--- a/httpx/_client.py
+++ b/httpx/_client.py
@@ -1738,7 +1738,7 @@ async def get(
         params: typing.Optional[QueryParamTypes] = None,
         headers: typing.Optional[HeaderTypes] = None,
         cookies: typing.Optional[CookieTypes] = None,
-        auth: typing.Union[AuthTypes, UseClientDefault, None] = USE_CLIENT_DEFAULT,
+        auth: typing.Union[AuthTypes, UseClientDefault] = USE_CLIENT_DEFAULT,
         follow_redirects: typing.Union[bool, UseClientDefault] = USE_CLIENT_DEFAULT,
         timeout: typing.Union[TimeoutTypes, UseClientDefault] = USE_CLIENT_DEFAULT,
         extensions: typing.Optional[RequestExtensions] = None,