diff --git a/stix2/test/v21/test_markings.py b/stix2/test/v21/test_markings.py
index 7e0cf91..a7dff22 100644
--- a/stix2/test/v21/test_markings.py
+++ b/stix2/test/v21/test_markings.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+
 import datetime as dt
 
 import pytest