diff --git a/run_qemu.sh b/run_qemu.sh
index c2bfdd7..be48fdc 100755
--- a/run_qemu.sh
+++ b/run_qemu.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+set -eu
+
 cachedir="./shared/cache"
 
 qemu-img create -f qcow2 -b "$cachedir/debian-unstable.qcow" debian-unstable-overlay.qcow