diff --git a/src/usbinstall.sh b/src/usbinstall.sh
index 8a2a799..10ae151 100755
--- a/src/usbinstall.sh
+++ b/src/usbinstall.sh
@@ -213,11 +213,14 @@ set_status "Copia del file iso di openmamba in corso..."
 ORIG_SIZE=`stat -c %s $SELECT_ISO`
 cp $SELECT_ISO ./ &
 DEST_SIZE=0
+DEST_FILE=./"`basename $SELECT_ISO`"
 while [ $ORIG_SIZE -gt $DEST_SIZE ]; do
-	DEST_SIZE=$(stat -c %s ./"`basename $SELECT_ISO`")
+    if [ -e $DEST_FILE ]; then
+	DEST_SIZE=$(stat -c %s $DEST_FILE)
 	percentuale=$((45 + ( 50 * $DEST_SIZE ) / $ORIG_SIZE ))
 	set_pbar $percentuale
-	sleep 2
+    fi
+    sleep 2
 done
 ln -fs `basename $SELECT_ISO` ./openmamba-live.iso
 popd >/dev/null