diff --git a/tests/utils.py b/tests/utils.py
index 9fe3531..60e7caa 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -35,7 +35,7 @@
 
     # We want to test only for a particular operation
     return [
-        tuple(vector[1][f] for f in fields)
+        tuple(vector[1][f].encode("ascii") for f in fields)
         for vector in sorted(data[op].items(), key=lambda v: v[0])
     ]