diff --git a/tests/test_utils.py b/tests/test_utils.py
index 9d2ee4a..26eb86f 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -257,13 +257,13 @@
     )
     assert vectors == [
         {
-            "key": "0123456789ABCDEFF0E1D2C3B4A59687",
-            "iv": "FEDCBA9876543210",
+            "key": b"0123456789ABCDEFF0E1D2C3B4A59687",
+            "iv": b"FEDCBA9876543210",
             "plaintext": (
-                "37363534333231204E6F77206973207468652074696D6520666F722000"
+                b"37363534333231204E6F77206973207468652074696D6520666F722000"
             ),
             "ciphertext": (
-                "E73214A2822139CAF26ECF6D2EB9E76E3DA3DE04D1517200519D57A6C3"
+                b"E73214A2822139CAF26ECF6D2EB9E76E3DA3DE04D1517200519D57A6C3"
             ),
         }
     ]