diff --git a/stix2/base.py b/stix2/base.py
index d4d63d8..f387022 100644
--- a/stix2/base.py
+++ b/stix2/base.py
@@ -1,8 +1,8 @@
 """Base class for type definitions in the stix2 library."""
 
 import collections
-import datetime as dt
 import copy
+import datetime as dt
 import json