diff --git a/src/usbinstall.py b/src/usbinstall.py
index 9744d61..c657222 100755
--- a/src/usbinstall.py
+++ b/src/usbinstall.py
@@ -159,12 +159,8 @@ def go_on():
 	cloud_hide()
 	# Step n°1 to n°2
 	if step == 1:
-		if path_cpio == "":
-			msg_warn(_("A file .cpio is required"))
-			return
-		else:
-			step += 1
-			step2()
+		step += 1
+		step2()
 	# Step n°2 to n°3
 	elif step == 2:
 		if path_iso == "":
diff --git a/src/usbinstall.sh b/src/usbinstall.sh
index f93039e..70681a5 100755
--- a/src/usbinstall.sh
+++ b/src/usbinstall.sh
@@ -173,35 +173,30 @@ else
 	errorAndExit $"Error(Arg 1): \"$1\" isn't a block device" 1
 fi
 
-# Check if Arg 2 is valid
-if [ -f "$2" ]; then	# Check if is a file
-	if [ -r "$2" ]; then	# Chek is is readable
-		export SELECT_BOOT=$2
-	else
-		errorAndExit $"Error(Arg 2): \"$2\" is not readable" 1
-	fi
-else
-	errorAndExit $"Error(Arg 2): \"$2\" isn't a regular file" 1
-fi
-# Check if Arg 2 is a gz file
-if [ "${2##*.}" != "gz" ]; then
-	errorAndExit "Error(Arg 2): you must chose a cpio.gz file" 1
+# Check if Arg 2 is valid (it can be null)
+if ["$2" ]; then
+   if [ -r "$2" ]; then	# Chek is is readable
+      # Check if Arg 2 is a gz file
+      if [ "${2##*.}" != "gz" ]; then
+         errorAndExit "Error(Arg 2): you must chose a cpio.gz file" 1
+      fi
+      export SELECT_BOOT=$2
+   else
+      errorAndExit $"Error(Arg 2): \"$2\" is not readable" 1
+   fi
 fi
 
 # Check if Arg 3 is valid
-if [ -f "$3" ]; then	# Check if is a file
-	if [ -r "$3" ]; then	# Chek is is readable
-		SELECT_ISO=`readlink -f $3`
-	else
-		errorAndExit "Error(Arg 3): \"$3\" is not readable" 1
-	fi
+if [ -r "$3" ]; then	# Chek is is readable
+   # Check if Arg 3 is an iso file
+   if [ "${3##*.}" != "iso" ]; then
+      errorAndExit "Error(Arg 3): you must chose a iso file" 1
+   fi
+   SELECT_ISO=`readlink -f $3`
 else
-	errorAndExit "Error(Arg 3): \"$3\" isn't a regular file" 1
-fi
-# Check if Arg 3 is an iso file
-if [ "${3##*.}" != "iso" ]; then
-	errorAndExit "Error(Arg 3): you must chose a iso file" 1
+   errorAndExit "Error(Arg 3): \"$3\" is not readable" 1
 fi
+
 #################################(INITIAL-CHECK)#####################################
 
 
@@ -306,20 +301,7 @@ if [ ! -d "$MOUNTDIR" ]; then
    errorAndExit $"Error: unable to found usb mount path"
 fi
 
-set_status $"Extracting bootusb archive..."
-echo $"Extracting bootusb archive..."
 pushd $MOUNTDIR >/dev/null
-sudo chmod 777 ./
-gunzip -c $SELECT_BOOT | cpio -i
-if [ ! -d "./boot" ]; then
-   errorAndExit $"Error: Invalid bootusb archive"
-fi
-set_pbar 38
-
-set_status $"Writing bootloader..."
-echo $"Writing bootloader..."
-sudo extlinux --install boot
-set_pbar 45
 
 set_status $"Copying ISO..."
 echo $"Copying ISO..."
@@ -333,13 +315,46 @@ ps $CPPID >/dev/null
 while [ $? -eq 0 ]; do
     if [ -e $DEST_FILE ]; then
 	DEST_SIZE=$(stat -c %s $DEST_FILE)
-	percentuale=$((45 + ( 50 * $DEST_SIZE ) / $ORIG_SIZE ))
+	percentuale=$((30 + ( 50 * $DEST_SIZE ) / $ORIG_SIZE ))
 	set_pbar $percentuale
     fi
     sleep 2
     ps $CPPID >/dev/null
 done
 ln -fs `basename $SELECT_ISO` ./openmamba-live.iso
+
+set_status $"Extracting bootusb archive..."
+echo $"Extracting bootusb archive..."
+sudo chmod 777 ./
+if [ "$SELECT_BOOT" ]; then
+   gunzip -c $SELECT_BOOT | cpio -i
+   if [ ! -d "./boot" ]; then
+      errorAndExit $"Error: Invalid bootusb archive"
+   fi
+else
+   ISOMOUNTDIR=`mktemp -d --suffix=.usbinstall`
+   mount -o loop $SELECT_ISO $ISOMOUNTDIR || {
+      errorAndExit $"Error: unable to mount ISO image"
+   }
+   mkdir boot
+   cp $ISOMOUNTDIR/boot/{initrd*,vmlinuz*} boot/
+   cp $ISOMOUNTDIR/boot/isolinux/* boot/
+   mv boot/isolinux.cfg boot/extlinux.conf
+   sed -i "s|root=[^[:space:]]*|root=live:/openmamba_live/openmamba-live.iso|" boot/extlinux.conf
+   cp /usr/share/syslinux/{libcom32,libutil,vesamenu}.c32 boot/ || {
+      errorAndExit $"Error: can't copy some files to /boot directory"
+   }
+   rm -f boot/isolinux*
+   umount $ISOMOUNTDIR
+   rmdir $ISOMOUNTDIR
+fi
+set_pbar 85
+
+set_status $"Writing bootloader..."
+echo $"Writing bootloader..."
+sudo extlinux --install boot
+set_pbar 90
+
 popd >/dev/null
 sync
 set_pbar 95