Fixed #1436 -- mark the multifernet tests as requiring the backends they need
diff --git a/tests/test_fernet.py b/tests/test_fernet.py
index 813ad88..1aa0417 100644
--- a/tests/test_fernet.py
+++ b/tests/test_fernet.py
@@ -26,7 +26,7 @@
 
 from cryptography.fernet import Fernet, InvalidToken, MultiFernet
 from cryptography.hazmat.backends import default_backend
-from cryptography.hazmat.backends.interfaces import CipherBackend
+from cryptography.hazmat.backends.interfaces import CipherBackend, HMACBackend
 from cryptography.hazmat.primitives.ciphers import algorithms, modes
 
 import cryptography_vectors
@@ -48,6 +48,7 @@
 
 
 @pytest.mark.requires_backend_interface(interface=CipherBackend)
+@pytest.mark.requires_backend_interface(interface=HMACBackend)
 @pytest.mark.supported(
     only_if=lambda backend: backend.cipher_supported(
         algorithms.AES("\x00" * 32), modes.CBC("\x00" * 16)
@@ -118,6 +119,8 @@
             Fernet(base64.urlsafe_b64encode(b"abc"), backend=backend)
 
 
+@pytest.mark.requires_backend_interface(interface=CipherBackend)
+@pytest.mark.requires_backend_interface(interface=HMACBackend)
 @pytest.mark.supported(
     only_if=lambda backend: backend.cipher_supported(
         algorithms.AES("\x00" * 32), modes.CBC("\x00" * 16)