diff --git a/build.sh b/build.sh
index b22c6af..498b7b1 100755
--- a/build.sh
+++ b/build.sh
@@ -1,8 +1,16 @@
-#!/bin/sh
-set -x
-set -eu
+#!/usr/bin/env bash
+set -eux
 
-docker build --platform linux/amd64 -t dr.zoemp.be/my-custom-app:$(cat VERSION) -f Dockerfile.cloudron .
-docker push dr.zoemp.be/my-custom-app:$(cat VERSION)
-cloudron update --image dr.zoemp.be/my-custom-app:$(cat VERSION) --app my-custom-app
+APP="${1:-shaarlitest}"
+VERSION="$(cat VERSION)"
+IMAGE="dr.zoemp.be/${APP}:${VERSION}"
+
+docker build --platform linux/amd64 -t "${IMAGE}" -f Dockerfile .
+docker push "${IMAGE}"
+
+if cloudron list | awk '{print $2}' | grep -q "^${APP}\.zoemp\.be$"; then
+    cloudron update --image "${IMAGE}" --app "${APP}"
+else
+    cloudron install --image "${IMAGE}" --location "${APP}"
+fi