diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index 2467996..7594fba 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -61,8 +61,8 @@
     def create_block_cipher_context(self, cipher, mode):
         ctx = self._ffi.new("EVP_CIPHER_CTX *")
         # TODO: compute name using a better algorithm
-        ciphername = b"{}-{}-{}".format(cipher.name, len(cipher.key) * 8, mode.name)
-        evp_cipher = self._lib.EVP_get_cipherbyname(ciphername)
+        ciphername = "{0}-{1}-{2}".format(cipher.name, len(cipher.key) * 8, mode.name)
+        evp_cipher = self._lib.EVP_get_cipherbyname(ciphername.encode("ascii"))
         if evp_cipher == self._ffi.NULL:
             raise OpenSSLError(self)
         # TODO: only use the key and initialization_vector as needed. Sometimes
diff --git a/tests/primitives/test_block.py b/tests/primitives/test_block.py
index f2da583..8c311d5 100644
--- a/tests/primitives/test_block.py
+++ b/tests/primitives/test_block.py
@@ -13,8 +13,8 @@
     )
     def test_aes_cbc_nopadding(self, key, iv, plaintext, ciphertext):
         cipher = BlockCipher(
-            ciphers.AES(binascii.unhexlify(key)),
-            modes.CBC(binascii.unhexlify(iv), padding.NoPadding())
+            ciphers.AES(binascii.unhexlify(key.encode("ascii"))),
+            modes.CBC(binascii.unhexlify(iv.encode("ascii")), padding.NoPadding())
         )
         actual_ciphertext = cipher.encrypt(binascii.unhexlify(plaintext))
         actual_ciphertext += cipher.finalize()