diff --git a/tests.sh b/tests.sh
index 0a7db480cb8c416cc7a72d05ce2112444c1bbc92..49c98e0a521cc91c1923b989571c4541bebeaee7 100755
--- a/tests.sh
+++ b/tests.sh
@@ -1,4 +1,5 @@
-#!/bin/sh -e
+#!/bin/sh
+set -eu
 
 export infile="$(mktemp)"
 export outfile="$(mktemp)"