diff --git a/bin/cert-gen.sh b/bin/cert-gen.sh
index c9bdffa1..2be643ae 100755
--- a/bin/cert-gen.sh
+++ b/bin/cert-gen.sh
@@ -3,6 +3,7 @@
 set -e
 
 DOMAIN=localhost
+[ ! -z "$1" ] && DOMAIN=$1
 
 CONFIG_DIR=$HOME/.lamassu
 LOG_FILE=/tmp/cert-gen.log