diff --git a/Dockerfile b/Dockerfile
index a2c5fe0..a3f9be5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM --platform=$BUILDPLATFORM golang:1.15-alpine AS builder
+FROM --platform=${BUILDPLATFORM} golang:1.15-alpine AS builder
 RUN apk add -U --no-cache \
   build-base \
   ca-certificates \
@@ -11,10 +11,10 @@ COPY go.mod .
 COPY go.sum .
 RUN go mod download
 COPY . .
-RUN ./_do_gen_assets
-RUN ./_do_build_server
+RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} ./_do_gen_assets
+RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} ./_do_build_server
 
-FROM --platform=$BUILDPLATFORM alpine:3.12.3
+FROM --platform=${BUILDPLATFORM} alpine:3.12.3
 RUN apk add -U --no-cache \
   ffmpeg \
   ca-certificates \