diff --git a/tests/flow_query.py b/tests/flow_query.py
index 403d138..271be11 100644
--- a/tests/flow_query.py
+++ b/tests/flow_query.py
@@ -63,6 +63,7 @@
 import unittest
 import random
 import time
+import copy
 
 from oftest import config
 import oftest.controller  as controller