diff --git a/src/usbinstall.sh b/src/usbinstall.sh
index cba99f1..1f69d04 100644
--- a/src/usbinstall.sh
+++ b/src/usbinstall.sh
@@ -282,8 +282,6 @@ else
 
    mkdir LiveOS boot rwroot ovlwork
    cp $ISOMOUNTDIR/boot/{initrd*,vmlinuz*} boot/
-   TARGET_ARCH=`cat $ISOMOUNTDIR/etc/openmamba-release | sed "s|.*for \(.*\) .*|\1|"`
-   [ "$TARGET_ARCH" ] || TARGET_ARCH=x86_64
 
    set_status $"Copying SquashFS image from ISO image..."
    echo $"Copying SquashFS image..."
@@ -304,8 +302,10 @@ else
        ps $CPPID >/dev/null
    done
    
-   # basic extlinux.conf -> grub.cfg conversion
-   echo "\
+   if [ -e $ISOMOUNTDIR/boot/isolinux/isolinux.cfg ]; then
+       # basic extlinux.conf -> grub.cfg conversion
+       # Legacy for old openmamba iso images with isolinux bootloader
+       echo "\
 #
 # GRUB configuration generated by openmamba usbinstall tool
 #
@@ -326,34 +326,39 @@ search --no-floppy --label --set=root openmamba_live
 # Boot entries taken from ISO bootloader
 #
 " > $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-   while read line; do
-      case $line in
-         "MENU LABEL "*) [ "$CURR_BRACKET_OPEN" = "1" ] && echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                         echo "menuentry \"${line/MENU LABEL }\" {" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                         CURR_BRACKET_OPEN=1
-                         ;;
-         "kernel "*) CURR_KERNEL="${line/kernel }"
-                      echo "echo \"Loading ${CURR_KERNEL}\"" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                      ;;
-         "append "*) set -- ${line/append initrd=}
-                      CURR_INITRD="$1"
-                      CURR_CMDLINE="${line/append initrd=$CURR_INITRD}"
-                      CURR_CMDLINE="${CURR_CMDLINE/vga=792}"
-                      echo "linux ${CURR_KERNEL} ${CURR_CMDLINE}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                      echo "echo \"Loading ${CURR_INITRD}\"" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                      echo "initrd ${CURR_INITRD}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                      echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-                      CURR_BRACKET_OPEN=0
-                      ;;
-      esac
-   done < $ISOMOUNTDIR/boot/isolinux/isolinux.cfg
-   [ "$CURR_BRACKET_OPEN" = "1" ] && echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
-   sed -i "s|root=live:LABEL=.*splash|root=live:LABEL=openmamba_live rd.live.overlay=/dev/disk/by-label/openmamba_live:/rwroot selinux=0 quiet splash rw|" $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+      while read line; do
+         case $line in
+            "MENU LABEL "*) [ "$CURR_BRACKET_OPEN" = "1" ] && echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                           echo "menuentry \"${line/MENU LABEL }\" {" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                           CURR_BRACKET_OPEN=1
+                           ;;
+            "kernel "*) CURR_KERNEL="${line/kernel }"
+                        echo "echo \"Loading ${CURR_KERNEL}\"" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                        ;;
+            "append "*) set -- ${line/append initrd=}
+                        CURR_INITRD="$1"
+                        CURR_CMDLINE="${line/append initrd=$CURR_INITRD}"
+                        CURR_CMDLINE="${CURR_CMDLINE/vga=792}"
+                        echo "linux ${CURR_KERNEL} ${CURR_CMDLINE}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                        echo "echo \"Loading ${CURR_INITRD}\"" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                        echo "initrd ${CURR_INITRD}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                        echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+                        CURR_BRACKET_OPEN=0
+                        ;;
+         esac
+      done < $ISOMOUNTDIR/boot/isolinux/isolinux.cfg
+      [ "$CURR_BRACKET_OPEN" = "1" ] && echo "}" >> $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+      sed -i "s|root=live:LABEL=.*splash|root=live:LABEL=openmamba_live rd.live.overlay=/dev/disk/by-label/openmamba_live:/rwroot selinux=0 quiet splash rw|" $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
 
-   mkdir boot/grub
-   cp $MOUNTDIR_EFI/EFI/BOOT/grub.cfg boot/grub/grub.cfg
-   umount $ISOMOUNTDIR
-   rmdir $ISOMOUNTDIR
+      mkdir boot/grub
+      cp $MOUNTDIR_EFI/EFI/BOOT/grub.cfg boot/grub/grub.cfg
+      umount $ISOMOUNTDIR
+      rmdir $ISOMOUNTDIR
+   else
+      cp -a $ISOMOUNTDIR/boot/grub boot/
+      sed -i "s|root=live:LABEL=[^[:space:]]*|root=live:LABEL=openmamba_live rd.live.overlay=/dev/disk/by-label/openmamba_live:/rwroot|" boot/grub/grub.cfg
+      cp boot/grub/grub.cfg $MOUNTDIR_EFI/EFI/BOOT/grub.cfg
+   fi
 fi
 set_pbar 85