diff --git a/requests/auth.py b/requests/auth.py
index 8ae2ec69..d1da4ee0 100644
--- a/requests/auth.py
+++ b/requests/auth.py
@@ -134,5 +134,5 @@ class HTTPDigestAuth(AuthBase):
         return r
 
     def __call__(self, r):
-        r.hooks['response'] = self.handle_401
+        r.register_hook('response', self.handle_401)
         return r