diff --git a/backend/Dockerfile b/backend/Dockerfile
index c30b4ff..deb1782 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,5 +1,5 @@
-# syntax=docker/dockerfile:1.20
-FROM cgr.dev/chainguard/go:latest as build
+# syntax=docker/dockerfile:1.21
+FROM cgr.dev/chainguard/go:latest AS build
 
 WORKDIR /src