diff --git a/kvmstats.sh b/kvmstats.sh
index 8967452..2daaa9d 100644
--- a/kvmstats.sh
+++ b/kvmstats.sh
@@ -4,6 +4,8 @@
 # files. On Debian, this command is provided by the 'html-xml-utils'
 # package.
 
+set -e -u
+
 usage () {
     echo 'usage: kvmstats.sh [-u K|M|G]'
     exit 1