diff --git a/src/usbinstall.sh b/src/usbinstall.sh
index 99c97fb..040b14a 100755
--- a/src/usbinstall.sh
+++ b/src/usbinstall.sh
@@ -149,6 +149,10 @@ if [ -f "$2" ]; then	# Check if is a file
 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
+fi
 
 # Check if Arg 3 is valid
 if [ -f "$3" ]; then	# Check if is a file
@@ -160,6 +164,10 @@ if [ -f "$3" ]; then	# Check if is a file
 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
+fi
 #################################(INITIAL-CHECK)#####################################
 
 
@@ -184,7 +192,7 @@ set_pbar 2
 set_status "Formattazione della chiavetta in corso..."
 sudo fdisk $SELECT_USB < ./fdisk_template
 if [ "$?" != "0" ]; then
-   errorAndExit "Error: fdisk ended with error"
+   errorAndExit "Error: fdisk exit with error"
 fi
 set_pbar 5