diff --git a/app/Dockerfile b/app/Dockerfile
index dc3de69..1814c1a 100644
--- a/app/Dockerfile
+++ b/app/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.9
+FROM alpine:3.24@sha256:28bd5fe8b56d1bd048e5babf5b10710ebe0bae67db86916198a6eec434943f8b
 ADD app /
 ADD index.html.tmpl /
 EXPOSE 80