diff --git a/src/usbinstall.sh b/src/usbinstall.sh
index 92b53ae..f93039e 100755
--- a/src/usbinstall.sh
+++ b/src/usbinstall.sh
@@ -246,17 +246,17 @@ if [ "$?" != "0" ]; then
    errorAndExit $"Error:"" \"parted\" "$"exit with error (see $LOGFILE)"
 fi
 # EFI partition
-sudo parted -s -- $SELECT_USB mkpart primary fat32 0 20M &>>$LOGFILE
+sudo parted -s -a optimal -- $SELECT_USB mkpart primary fat32 0 20M &>>$LOGFILE
 if [ "$?" != "0" ]; then
    errorAndExit $"Error:"" \"parted\" "$"exit with error (see $LOGFILE)"
 fi
 # openmamba partition
-sudo parted -s -- $SELECT_USB mkpart primary ext4 20M -1 &>>$LOGFILE
+sudo parted -s -a optimal -- $SELECT_USB mkpart primary ext4 20M -1 &>>$LOGFILE
 if [ "$?" != "0" ]; then
    errorAndExit $"Error:"" \"parted\" "$"exit with error (see $LOGFILE)"
 fi
 # boot flag on openmamba partition
-sudo parted -s -- $SELECT_USB set 2 boot on &>>$LOGFILE
+sudo parted -s $SELECT_USB set 2 boot on &>>$LOGFILE
 if [ "$?" != "0" ]; then
    errorAndExit $"Error:"" \"parted\" "$"exit with error (see $LOGFILE)"
 fi
@@ -275,12 +275,29 @@ if [ "$?" != "0" ]; then
 fi
 
 sleep 1
+LANG=C udisks --mount ${SELECT_USB}1 &>>$LOGFILE
+if [ "$?" != "0" ]; then
+   errorAndExit $"Error:"" \"udisks --mount\" "$"exit with error (see $LOGFILE)"
+fi
 LANG=C udisks --mount ${SELECT_USB}2 &>>$LOGFILE
 if [ "$?" != "0" ]; then
    errorAndExit $"Error:"" \"udisks --mount\" "$"exit with error (see $LOGFILE)"
 fi
 set_pbar 30
 
+# Riceve la mountdir della chiavetta da dbus
+MOUNTDIR_EFI=`dbus_properties_get_stringlist org.freedesktop.UDisks /org/freedesktop/UDisks/devices/${SELECT_USB/*\/}1 \
+org.freedesktop.UDisks.Device DeviceMountPaths`
+
+if [ ! -d "$MOUNTDIR_EFI" ]; then
+   errorAndExit $"Error: unable to found usb mount path"
+fi
+
+mkdir -p $MOUNTDIR_EFI/EFI/BOOT/
+for f in /usr/lib/grub/bootx64.efi /usr/lib/grub/bootia32.efi; do
+   [ -e $f ] && cp $f $MOUNTDIR_EFI/EFI/BOOT/
+done
+
 # Riceve la mountdir della chiavetta da dbus
 MOUNTDIR=`dbus_properties_get_stringlist org.freedesktop.UDisks /org/freedesktop/UDisks/devices/${SELECT_USB/*\/}2 \
 org.freedesktop.UDisks.Device DeviceMountPaths`
@@ -302,10 +319,8 @@ set_pbar 38
 set_status $"Writing bootloader..."
 echo $"Writing bootloader..."
 sudo extlinux --install boot
-sudo install-mbr -e 1 $SELECT_USB
 set_pbar 45
 
-
 set_status $"Copying ISO..."
 echo $"Copying ISO..."
 # Copy code
@@ -327,13 +342,20 @@ done
 ln -fs `basename $SELECT_ISO` ./openmamba-live.iso
 popd >/dev/null
 sync
-set_pbar 98
+set_pbar 95
 
 set_status $"Unmount usb device"
 echo $"Unmount usb device"
-LANG=C udisks --unmount ${SELECT_USB}2 |  grep failed && { 
+LANG=C udisks --unmount ${SELECT_USB}1 | grep failed && {
+	errorAndExit $"Error: fail to umount the usb key (${SELECT_USB}1)"
+}
+LANG=C udisks --unmount ${SELECT_USB}2 | grep failed && {
 	errorAndExit $"Error: fail to umount the usb key (${SELECT_USB}2)"
 }
+
+# WARNING: calling install-mbr after unmounting to prevent problems of FAT since EFI partition introduction
+sudo install-mbr $SELECT_USB
+
 set_pbar 100
 exit_frontend ""
 echo $"Done!"