diff --git a/app/Dockerfile b/app/Dockerfile
index dc3de69..9f035ff 100644
--- a/app/Dockerfile
+++ b/app/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.9
+FROM alpine:3.24@sha256:a2d49ea686c2adfe3c992e47dc3b5e7fa6e6b5055609400dc2acaeb241c829f4
 ADD app /
 ADD index.html.tmpl /
 EXPOSE 80