diff --git a/myhdl/test/core/test_concat.py b/myhdl/test/core/test_concat.py
index 812eb7d0..8f10a9c5 100644
--- a/myhdl/test/core/test_concat.py
+++ b/myhdl/test/core/test_concat.py
@@ -25,12 +25,14 @@ import unittest
 from unittest import TestCase
 import random
 from random import randrange
+from functools import reduce
 random.seed(2) # random, but deterministic
 import operator
 
 from myhdl._intbv import intbv
 from myhdl._Signal import Signal
 from myhdl._concat import concat
+from myhdl._compat import long