diff --git a/usr.sbin/pc-sysinstall/backend-partmanager/create-part.sh b/usr.sbin/pc-sysinstall/backend-partmanager/create-part.sh
index 407c9a46e07..ccb8d19ec27 100755
--- a/usr.sbin/pc-sysinstall/backend-partmanager/create-part.sh
+++ b/usr.sbin/pc-sysinstall/backend-partmanager/create-part.sh
@@ -85,7 +85,7 @@ fi
 
 # If this is an empty disk, see if we need to create a new scheme for it
 gpart show ${DISK} >/dev/null 2>/dev/null
-if [ "$?" != "0" -a "${SLICENUM}" = "1" ] ; then
+if [ $? -eq 0 -a "${SLICENUM}" = "1" ] ; then
  gpart create -s ${TYPE} ${DISK}
 fi
 
diff --git a/usr.sbin/pc-sysinstall/backend-partmanager/delete-part.sh b/usr.sbin/pc-sysinstall/backend-partmanager/delete-part.sh
index e786d4047ee..c444f65bc40 100755
--- a/usr.sbin/pc-sysinstall/backend-partmanager/delete-part.sh
+++ b/usr.sbin/pc-sysinstall/backend-partmanager/delete-part.sh
@@ -57,10 +57,10 @@ PARTINDEX=""
 while 
 z=1
 do
-  CHARS=`expr $CHARS - 1`
+  CHARS=$((CHARS-1))
   LAST_CHAR=`echo "${PARTITION}" | cut -c $CHARS`
-  echo "${LAST_CHAR}" | grep "^[0-9]$" >/dev/null 2>/dev/null
-  if [ "$?" = "0" ] ; then
+  echo "${LAST_CHAR}" | grep -q "^[0-9]$" 2>/dev/null
+  if [ $? -eq 0 ] ; then
     PARTINDEX="${LAST_CHAR}${PARTINDEX}"
   else
     break