2 files changed, 8 insertions, 4 deletions
diff --git a/cryptography/hazmat/primitives/twofactor/hotp.py b/cryptography/hazmat/primitives/twofactor/hotp.py
index bac23d1b..41c467c8 100644
--- a/cryptography/hazmat/primitives/twofactor/hotp.py
+++ b/cryptography/hazmat/primitives/twofactor/hotp.py
@@ -17,7 +17,9 @@ import struct
 
 import six
 
-from cryptography.exceptions import InvalidToken, UnsupportedAlgorithm, _Causes
+from cryptography.exceptions import (
+    InvalidToken, UnsupportedAlgorithm, _Reasons
+)
 from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import constant_time, hmac
 from cryptography.hazmat.primitives.hashes import SHA1, SHA256, SHA512
@@ -28,7 +30,7 @@ class HOTP(object):
         if not isinstance(backend, HMACBackend):
             raise UnsupportedAlgorithm(
                 "Backend object does not implement HMACBackend",
-                _Causes.BACKEND_MISSING_INTERFACE
+                _Reasons.BACKEND_MISSING_INTERFACE
             )
 
         if len(key) < 16:
diff --git a/cryptography/hazmat/primitives/twofactor/totp.py b/cryptography/hazmat/primitives/twofactor/totp.py
index d0162395..e55ba00d 100644
--- a/cryptography/hazmat/primitives/twofactor/totp.py
+++ b/cryptography/hazmat/primitives/twofactor/totp.py
@@ -13,7 +13,9 @@
 
 from __future__ import absolute_import, division, print_function
 
-from cryptography.exceptions import InvalidToken, UnsupportedAlgorithm, _Causes
+from cryptography.exceptions import (
+    InvalidToken, UnsupportedAlgorithm, _Reasons
+)
 from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import constant_time
 from cryptography.hazmat.primitives.twofactor.hotp import HOTP
@@ -24,7 +26,7 @@ class TOTP(object):
         if not isinstance(backend, HMACBackend):
             raise UnsupportedAlgorithm(
                 "Backend object does not implement HMACBackend",
-                _Causes.BACKEND_MISSING_INTERFACE
+                _Reasons.BACKEND_MISSING_INTERFACE
             )
 
         self._time_step = time_step