diff --git a/third_party/2and3/cryptography/hazmat/primitives/ciphers/__init__.pyi b/third_party/2and3/cryptography/hazmat/primitives/ciphers/__init__.pyi
index 547a288d8..321ecbc1b 100644
--- a/third_party/2and3/cryptography/hazmat/primitives/ciphers/__init__.pyi
+++ b/third_party/2and3/cryptography/hazmat/primitives/ciphers/__init__.pyi
@@ -1,4 +1,5 @@
 from abc import ABCMeta, abstractmethod
+from typing import Optional
 
 from cryptography.hazmat.backends.interfaces import CipherBackend
 from cryptography.hazmat.primitives.ciphers.modes import Mode
@@ -22,7 +23,7 @@ class BlockCipherAlgorithm(metaclass=ABCMeta):
     def block_size(self) -> int: ...
 
 class Cipher(object):
-    def __init__(self, algorithm: CipherAlgorithm, mode: Mode, backend: CipherBackend) -> None: ...
+    def __init__(self, algorithm: CipherAlgorithm, mode: Optional[Mode], backend: CipherBackend) -> None: ...
     def decryptor(self) -> CipherContext: ...
     def encryptor(self) -> CipherContext: ...