diff --git a/Dockerfile.amd64 b/Dockerfile.amd64
index bf9c057..905847c 100644
--- a/Dockerfile.amd64
+++ b/Dockerfile.amd64
@@ -1,9 +1,11 @@
 ################################################################################
 # base system
 ################################################################################
-FROM ubuntu:18.04 as system
+ARG image
+FROM $image as system
 
 ARG localbuild
+RUN echo "LOCALBUILD=$localbuild"
 RUN if [ "x$localbuild" != "x" ]; then sed -i 's#http://archive.ubuntu.com/#http://tw.archive.ubuntu.com/#' /etc/apt/sources.list; fi
 
 # && add-apt-repository ppa:fcwu-tw/apps  x11vnc
@@ -26,7 +28,7 @@ RUN apt-get update \
 # Additional packages require ~600MB
 # libreoffice  pinta language-pack-zh-hant language-pack-gnome-zh-hant firefox-locale-zh-hant libreoffice-l10n-zh-tw
 
-# tini for subreap                                   
+# tini for subreap
 ARG TINI_VERSION=v0.18.0
 ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /bin/tini
 RUN chmod +x /bin/tini
diff --git a/Makefile b/Makefile
index 6ba9aa7..6d07a07 100644
--- a/Makefile
+++ b/Makefile
@@ -2,9 +2,11 @@
 
 REPO  ?= dorowu/ubuntu-desktop-lxde-vnc
 TAG   ?= latest
+IMAGE ?= ubuntu:18.04
+LOCALBUILD ?= 1
 
 build:
-	docker build -t $(REPO):$(TAG) --build-arg localbuild=1 .
+	docker build -t $(REPO):$(TAG) --build-arg localbuild=$(LOCALBUILD) --build-arg image=$(IMAGE) .
 
 run:
 	docker run --rm \