diff --git a/cryptography/fernet.py b/cryptography/fernet.py
index 4220e0c..2de4a62 100644
--- a/cryptography/fernet.py
+++ b/cryptography/fernet.py
@@ -25,7 +25,9 @@
     def _encrypt_from_parts(self, data, current_time, iv):
         padder = padding.PKCS7(ciphers.AES.block_size).padder()
         padded_data = padder.update(data) + padder.finalize()
-        encryptor = BlockCipher(ciphers.AES(self.encryption_key), modes.CBC(iv)).encryptor()
+        encryptor = BlockCipher(
+            ciphers.AES(self.encryption_key), modes.CBC(iv)
+        ).encryptor()
         ciphertext = encryptor.update(padded_data) + encryptor.finalize()
 
         h = HMAC(self.signing_key, digestmod=hashes.SHA256)
@@ -55,11 +57,14 @@
         hmac = h.digest()
         if not constant_time_compare(hmac, data[-32:]):
             raise ValueError
-        decryptor = BlockCipher(ciphers.AES(self.encryption_key), modes.CBC(iv)).decryptor()
+        decryptor = BlockCipher(
+            ciphers.AES(self.encryption_key), modes.CBC(iv)
+        ).decryptor()
         plaintext_padded = decryptor.update(ciphertext) + decryptor.finalize()
         unpadder = padding.PKCS7(ciphers.AES.block_size).unpadder()
         return unpadder.update(plaintext_padded) + unpadder.finalize()
 
+
 def constant_time_compare(a, b):
     # TOOD: replace with a cffi function
     assert isinstance(a, bytes) and isinstance(b, bytes)
diff --git a/tests/test_fernet.py b/tests/test_fernet.py
index f7c06b9..27d2418 100644
--- a/tests/test_fernet.py
+++ b/tests/test_fernet.py
@@ -1,5 +1,7 @@
 import base64
 
+import six
+
 from cryptography.fernet import Fernet
 
 
@@ -11,10 +13,10 @@
         token = f._encrypt_from_parts(
             b"hello",
             499162800,
-            b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F",
+            b"".join(map(six.int2byte, range(16))),
         )
         assert token == (b"gAAAAAAdwJ6wAAECAwQFBgcICQoLDA0ODy021cpGVWKZ_eEwCGM"
-                          "4BLLF_5CV9dOPmrhuVUPgJobwOz7JcbmrR64jVmpU4IwqDA==")
+                         "4BLLF_5CV9dOPmrhuVUPgJobwOz7JcbmrR64jVmpU4IwqDA==")
 
     def test_verify(self):
         f = Fernet(base64.urlsafe_b64decode(
@@ -22,7 +24,7 @@
         ))
         payload = f.decrypt(
             (b"gAAAAAAdwJ6wAAECAwQFBgcICQoLDA0ODy021cpGVWKZ_eEwCGM4BLLF_5CV9dO"
-              "PmrhuVUPgJobwOz7JcbmrR64jVmpU4IwqDA=="),
+             "PmrhuVUPgJobwOz7JcbmrR64jVmpU4IwqDA=="),
             ttl=60,
             current_time=499162801
         )