diff --git a/sfmldemo/reset_build.sh b/sfmldemo/reset_build.sh
index ac16c1b..caf96c3 100755
--- a/sfmldemo/reset_build.sh
+++ b/sfmldemo/reset_build.sh
@@ -1,3 +1,6 @@
+#!/usr/bin/env bash
+set -ex
+
 mv ./subprojects/packagecache .
 rm -rf ./subprojects ./builddir
 mkdir subprojects