diff --git a/test.sh b/test.sh
index 41443a2..bc4171b 100755
--- a/test.sh
+++ b/test.sh
@@ -265,6 +265,7 @@ for hostname in "${machines[@]}"; do
         )
         ;;
     *)
+        printf "unknown hostname: %s\n" "${hostname}" >&2
         exit 1
         ;;
     esac