diff --git a/jenkins/Jenkinsfile.preview-deployer b/jenkins/Jenkinsfile.preview-deployer
index 6591da10f..3f4e5961e 100644
--- a/jenkins/Jenkinsfile.preview-deployer
+++ b/jenkins/Jenkinsfile.preview-deployer
@@ -47,6 +47,10 @@ pipeline {
       steps {
         sh '''
           set -euo pipefail
+          ACTION="${ACTION:-}"
+          SOURCE_BRANCH="${SOURCE_BRANCH:-}"
+          COMMIT_HASH="${COMMIT_HASH:-}"
+          DEPLOYMENT_ID="${DEPLOYMENT_ID:-}"
           case "${ACTION}" in DEPLOY|STATUS|UNINSTALL) ;; *) exit 1 ;; esac
           if [ -n "${SOURCE_BRANCH}" ]; then
             git check-ref-format --branch "${SOURCE_BRANCH}" >/dev/null