diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index 657c98cd723e..60fb3b0656c1 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -1893,6 +1893,8 @@ static int do_cmd_ioctl(struct comedi_device *dev,
 
 	ret = s->do_cmdtest(dev, s, &async->cmd);
 
+	kfree(cmd->chanlist);   /* free kernel copy of user chanlist */
+
 	if (async->cmd.flags & CMDF_BOGUS || ret) {
 		dev_dbg(dev->class_dev, "test returned %d\n", ret);
 		*cmd = async->cmd;