diff --git a/ubuntu_mates.sh b/ubuntu_mates.sh
index 39fd7d1..fe3c432 100644
--- a/ubuntu_mates.sh
+++ b/ubuntu_mates.sh
@@ -1,2 +1,4 @@
+#!/bin/sh
+
 # Faster Ubuntu APT repository server for Korean
 sudo sed -i 's/kr.archive.ubuntu.com/mirror.kakao.com/g' /etc/apt/sources.list