diff --git a/tools/build-docker-certs.sh b/tools/build-docker-certs.sh
index e2dd1b90..a7c90156 100644
--- a/tools/build-docker-certs.sh
+++ b/tools/build-docker-certs.sh
@@ -23,7 +23,7 @@ decho () {
   echo `date +"%H:%M:%S"` $1
 }
 
-IP=$(hostname -i)
+IP=$HOSTNAME
 NODE_MODULES=$(npm -g root)
 NPM_BIN=$(npm -g bin)