diff --git a/Dockerfile b/Dockerfile
index 1453c65..959e3af 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.7
+# syntax=docker/dockerfile:1.9
 FROM curlimages/curl:latest as fetcher
 
 ARG WAITFOR_VERSION=2.2.4