diff --git a/cluster/ubuntu/download-release.sh b/cluster/ubuntu/download-release.sh
index 54441298850..fb4676f574f 100755
--- a/cluster/ubuntu/download-release.sh
+++ b/cluster/ubuntu/download-release.sh
@@ -64,7 +64,9 @@ function get_latest_version_number {
   fi
 }
 
-KUBE_VERSION=$(get_latest_version_number | sed 's/^v//')
+if [ -z "$KUBE_VERSION" ]; then
+  KUBE_VERSION=$(get_latest_version_number | sed 's/^v//')
+fi
 
 # k8s
 echo "Prepare kubernetes ${KUBE_VERSION} release ..."