diff --git a/artiq/coredevice/comm_dummy.py b/artiq/coredevice/comm_dummy.py
index 84aafb666..807f83ca5 100644
--- a/artiq/coredevice/comm_dummy.py
+++ b/artiq/coredevice/comm_dummy.py
@@ -1,7 +1,7 @@
 from operator import itemgetter
 
 from artiq.language.db import AutoDB
-from artiq.language.units import ms, ns
+from artiq.language.units import ms
 from artiq.coredevice.runtime import LinkInterface