diff --git a/ssl-certificate.sh b/ssl-certificate.sh
index 64d75b1..8adb446 100644
--- a/ssl-certificate.sh
+++ b/ssl-certificate.sh
@@ -5,6 +5,7 @@
 # April 20th, 2018
 # Version 1.0: initial script
 #######################################################
+#!/bin/bash
 ###global function to update and cleanup the environment
 function update_and_clean() {
 apt update