diff --git a/contrib/debian/init.d/ebusd b/contrib/debian/init.d/ebusd
old mode 100755
new mode 100644
index 34e3d3e0..0bb1680d
--- a/contrib/debian/init.d/ebusd
+++ b/contrib/debian/init.d/ebusd
@@ -34,7 +34,10 @@ start_instance () {
 	shift
 	suffix="${opts#EBUSD_OPTS}"
 	dev=`echo " ${!opts}"|sed -e 's#^.* -d ##' -e 's# -.*$##'`
-	if [ -n "$dev" ] && [ "${dev:0:5}" == '/dev/' ] && [ -c "$dev" ] && [ -x /bin/setserial ]; then
+	if [ -z "$dev" ]; then
+		dev=/dev/ttyUSB0
+	fi
+	if [ "${dev:0:5}" == '/dev/' ] && [ -c "$dev" ] && [ -x /bin/setserial ]; then
 		log_daemon_msg "Setting low latency for ebusd${suffix} device"
 		/bin/setserial "$dev" low_latency
 		log_end_msg $?