--- /var/db/repos/gentoo/net-misc/minissdpd/files/minissdpd.initd-r2	2016-05-18 15:38:34.000000000 +0900
+++ /var/db/repos/gentoo/net-misc/minissdpd/files/minissdpd.initd-r2	2020-01-27 21:54:23.000000000 +0900
@@ -11,9 +11,9 @@ 
 interfaceup() {
 	# interface exists?
 	if [ ! -f /sys/class/net/$1/flags ]; then return 1; fi
-	let "IFUP = `cat /sys/class/net/$1/flags` & 1"
+	IFUP="$(($(cat /sys/class/net/$1/flags) & 1))"
 	# interface has UP flag?
-	if [ $IFUP -eq 0 ]; then return 1; fi
+	if [ "$IFUP" -eq 0 ]; then return 1; fi
 	return 0
 }