diff --git a/xCAT-nbroot/overlay/etc/init.d/S10autodetect b/xCAT-nbroot/overlay/etc/init.d/S10autodetect
index 3f0c14b1e..2421cf002 100755
--- a/xCAT-nbroot/overlay/etc/init.d/S10autodetect
+++ b/xCAT-nbroot/overlay/etc/init.d/S10autodetect
@@ -96,10 +96,10 @@ done
 
 
 
-((extrat=0))
+extrat=0
 until [ $extrat = 80 -o -z "$NICSTOWAIT" ]; do
    sleep 1
-   ((extrat=extrat+1))
+   extrat=$(($extrat+1))
    for nic in $NICSTOWAIT; do 
       if ifconfig $nic|grep "inet addr"; then
          NICSTOWAIT=`echo $NICSTOWAIT|sed -e s/$nic//`
diff --git a/xCAT-nbroot/overlay/etc/init.d/S11stunnel b/xCAT-nbroot/overlay/etc/init.d/S11stunnel
index 5f003a462..8b4b7ed03 100755
--- a/xCAT-nbroot/overlay/etc/init.d/S11stunnel
+++ b/xCAT-nbroot/overlay/etc/init.d/S11stunnel
@@ -22,12 +22,12 @@ if [ ! -z "$XCATDEST" ]; then
    echo 'connect='$XCATDEST >> /etc/stunnel/stunnel.conf
 fi
 if [ -r /tmp/dhcpserver ]; then 
-   ((i=400));
+   i=400;
    for srv in `cat /tmp/dhcpserver`; do
     echo "[xcatd$i]" >> /etc/stunnel/stunnel.conf
     echo "accept=127.0.0.1:$i" >> /etc/stunnel/stunnel.conf
     echo "connect="$srv":"$XCATPORT >> /etc/stunnel/stunnel.conf
-    ((i=i+1))
+    i=$(($i+1))
    done
 fi
 mkdir -p /usr/var/run/stunnel