diff --git a/src/usr/local/sbin/ppp-linkdown b/src/usr/local/sbin/ppp-linkdown
index 933e9fa91e..19429ad004 100755
--- a/src/usr/local/sbin/ppp-linkdown
+++ b/src/usr/local/sbin/ppp-linkdown
@@ -27,7 +27,7 @@ if [ -f /tmp/${IF}up ] && [ -f /conf/${IF}.log ]; then
 	/usr/local/sbin/ppp-log-uptime.sh $seconds ${IF} &
 fi
 
-if [ ${IF} !=~ "ppp[0-9]*" ]; then
+if echo "${IF}" | egrep -qv "ppp[0-9]+"; then
 	/etc/rc.kill_states ${IF} ${LOCAL_IP}
 fi