1 files changed, 1 insertions, 1 deletions
diff --git a/genpki.sh b/genpki.sh
index d41d3b8..6afb160 100755
--- a/genpki.sh
+++ b/genpki.sh
@@ -7,7 +7,7 @@ set -xe
 cd $(dirname $0)
 
 CLUSTER="$1"
-if [ ! -d "cluster/$CLUSTER" ]; then
+if [ -z "$CLUSTER" ] || [ ! -d "cluster/$CLUSTER" ]; then
 	echo "Usage: $0 <cluster name>"
 	echo "The cluster name must be the name of a subdirectory of cluster/"
 	exit 1