diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index b8fb495..040bbd1 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -69,7 +69,7 @@ jobs:
         uses: docker/build-push-action@v7
         with:
           context: .
-          platforms: linux/amd64
+          platforms: linux/amd64,linux/arm64
           push: ${{ env.PUSH == 'true' }}
           tags: ${{ steps.v.outputs.tags }}
           labels: |
diff --git a/Dockerfile b/Dockerfile
index 27c87a8..84f475e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,9 @@
 # mock-llmd: one static Go binary on distroless.
 
-FROM golang:1.27 AS build
+# Multi-arch: Go cross-compiles, so the build stage runs on the builder's own
+# platform and only the runtime stage is per-target -- no emulation needed.
+FROM --platform=$BUILDPLATFORM golang:1.27 AS build
+ARG TARGETOS TARGETARCH
 
 WORKDIR /src
 COPY go.mod go.sum ./
@@ -8,7 +11,7 @@ RUN go mod download
 
 # Only the sources: a locally built ./mock-llmd binary in the checkout stays out.
 COPY *.go ./
-RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/mock-llmd .
+RUN CGO_ENABLED=0 GOOS="${TARGETOS}" GOARCH="${TARGETARCH}" go build -trimpath -ldflags="-s -w" -o /out/mock-llmd .
 
 FROM gcr.io/distroless/static-debian12:nonroot