diff --git a/raspi-config b/raspi-config
index 2809968c..adbf04df 100755
--- a/raspi-config
+++ b/raspi-config
@@ -328,7 +328,7 @@ do_blanking() {
       CURRENT=1
   fi
   if [ "$INTERACTIVE" = True ]; then
-    if [ "$(dpkg -l xscreensaver | tail -n 1 | cut -d ' ' -f 1)" = "ii" ]; then
+    if is_installed xscreensaver; then
       whiptail --msgbox "Warning: xscreensaver is installed may override raspi-config settings" 20 60 2
     fi
     whiptail --yesno "Would you like to enable screen blanking?" $DEFAULT 20 60 2
@@ -1142,7 +1142,7 @@ ExecStart=-/sbin/agetty --autologin $USER --noclear %I \$TERM
 EOF
         ;;
       B3*)
-        if [ -e /etc/init.d/lightdm ]; then
+        if is_installed lightdm; then
           systemctl set-default graphical.target
           ln -fs /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@tty1.service
           rm /etc/systemd/system/getty@tty1.service.d/autologin.conf
@@ -1154,7 +1154,7 @@ EOF
         fi
         ;;
       B4*)
-        if [ -e /etc/init.d/lightdm ]; then
+        if is_installed lightdm; then
           systemctl set-default graphical.target
           ln -fs /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@tty1.service
           cat > /etc/systemd/system/getty@tty1.service.d/autologin.conf << EOF
@@ -1551,7 +1551,7 @@ do_gldriver() {
     return 1
   fi
   for package in gldriver-test libgl1-mesa-dri; do
-    if [ "$(dpkg -l "$package" 2> /dev/null | tail -n 1 | cut -d ' ' -f 1)" != "ii" ]; then
+    if ! is_installed "$package"; then
       missing_packages="$package $missing_packages"
     fi
   done