diff --git a/tests/test_src_handler.py b/tests/test_src_handler.py
index 0be1533..b2357e5 100644
--- a/tests/test_src_handler.py
+++ b/tests/test_src_handler.py
@@ -20,7 +20,6 @@
 from crcmod.predefined import PredefinedCrc
 from pyfakefs.fake_filesystem_unittest import TestCase
 from spacepackets.cfdp import (
-    NULL_CHECKSUM_U32,
     ChecksumType,
     ConditionCode,
     FinishedParams,