diff --git a/mk_mmc.sh b/mk_mmc.sh
index 6cbb5b5..d9b5328 100755
--- a/mk_mmc.sh
+++ b/mk_mmc.sh
@@ -1,3 +1,4 @@
+#!/bin/bash -e
 #
 # Copyright (c) 2009-2013 Robert Nelson <robertcnelson@gmail.com>
 #