diff --git a/include/lib.sh b/include/lib.sh
index 93680ce..c5790bf 100644
--- a/include/lib.sh
+++ b/include/lib.sh
@@ -174,6 +174,6 @@ x_()
 
 err_()
 {
-	printf "ERROR %s: %s\n" "$0" "$1" 1>&2
+	[ $# -lt 1 ] || printf "ERROR %s: %s\n" "$0" "$1" 1>&2 || :
 	exit 1
 }