diff --git a/Dockerfile b/Dockerfile
index 54061a4..147e293 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,8 @@
-FROM caddy:2.8.4-builder-alpine AS builder
+FROM caddy:2.8.4-builder-alpine@sha256:98bd4545236c1aae8afab0eca255903487925e92ca06f14accf7e9ca607a163e AS builder
 
 RUN xcaddy build \
     --with github.com/caddy-dns/rfc2136@master
 
-FROM caddy:2.8.4-alpine
+FROM caddy:2.8.4-alpine@sha256:e97e0e3f8f51be708a9d5fadbbd75e3398c22fc0eecd4b26d48561e3f7daa9eb
 
 COPY --from=builder /usr/bin/caddy /usr/bin/caddy
\ No newline at end of file