FROM dynamic args are not supported

docker-compose.yml

@@ -13,8 +13,7 @@ services:
       context: ./docker/sia
       dockerfile: Dockerfile
       args:
-        builder: alpine-1.5.0
-        branch: master
+        branch: v1.5.0
     container_name: sia
     restart: unless-stopped
     environment:

docker/sia/Dockerfile

@@ -4,11 +4,10 @@ ENV GOOS linux
 ENV GOARCH amd64
 
 ARG branch=master
-ARG builder=latest
 
 RUN git clone https://gitlab.com/NebulousLabs/Sia.git --single-branch --branch ${branch}
 RUN make release --directory Sia
 
-FROM nebulouslabs/sia:${builder}
+FROM nebulouslabs/sia:alpine-1.5.0
 
 COPY --from=sia-builder /go/bin/siac /go/bin/siad /usr/bin/