diff --git a/mythril/analysis/modules/transaction_order_dependence.py b/mythril/analysis/modules/transaction_order_dependence.py
index 4528459c..9db7c104 100644
--- a/mythril/analysis/modules/transaction_order_dependence.py
+++ b/mythril/analysis/modules/transaction_order_dependence.py
@@ -1,5 +1,6 @@
 import logging
 import re
+import copy
 
 from mythril.analysis import solver
 from mythril.analysis.ops import *