diff --git a/Dockerfile b/Dockerfile
index d7160aa..f7c07ca 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 
-FROM alpine:3 as rootfs-stage
+FROM alpine:3 AS rootfs-stage
 
 # environment
 ENV ROOTFS=/root-out
diff --git a/Dockerfile.aarch64 b/Dockerfile.aarch64
index 21375bc..c64265c 100644
--- a/Dockerfile.aarch64
+++ b/Dockerfile.aarch64
@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 
-FROM alpine:3 as rootfs-stage
+FROM alpine:3 AS rootfs-stage
 
 # environment
 ENV ROOTFS=/root-out