diff --cc scripts/release.sh
index 16ecf13,624d539..624d539
mode 100644,100755..100755
--- a/scripts/release.sh
+++ b/scripts/release.sh
@@@ -1,4 -1,5 +1,5 @@@
  #!/bin/sh
  set -eu
  VERSION="$1"
+ test -n "$VERSION" || { echo "usage: release.sh <version>" >&2; exit 2; }
  echo "tagging $VERSION"