diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
index a585a19..ca5e4b3 100644
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@@ -22,35 +22,14 @@ jobs:
     needs: format
     runs-on: ubuntu-latest
     container:
-      image: jaypoch/lumabuilder:latest
+      image: jaypoch/luma-markdown-builder:latest
+    env:
+      PATH: /root/.cargo/bin:/usr/local/bin:/usr/bin:/bin
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Install native packaging tools
-        run: |
-          set -eu
-          export PATH="$HOME/.cargo/bin:$PATH"
-
-          if ! command -v rustup >/dev/null 2>&1; then
-            curl --fail --silent --show-error https://sh.rustup.rs \
-              | sh -s -- -y --profile minimal
-          fi
-          export PATH="$HOME/.cargo/bin:$PATH"
-          rustup default stable
-
-          if ! command -v zig >/dev/null 2>&1; then
-            curl --fail --silent --show-error --location \
-              https://ziglang.org/download/0.16.0/zig-x86_64-linux-0.16.0.tar.xz \
-              --output /tmp/zig.tar.xz
-            tar -xJf /tmp/zig.tar.xz -C /tmp
-            ln -s /tmp/zig-x86_64-linux-0.16.0/zig "$HOME/.cargo/bin/zig"
-          fi
-
-          cargo install --locked queso
-          cargo install cargo-zigbuild
-
       - name: Build x86_64 and ARM64 binaries
         run: ./scripts/build-linux-binaries.sh
 
diff --git a/Dockerfile.luma-builder b/Dockerfile.luma-builder
new file mode 100644
index 0000000..7a5c399
--- /dev/null
+++ b/Dockerfile.luma-builder
@@ -0,0 +1,71 @@
+FROM alpine:3.20
+
+ARG TARGETARCH
+
+RUN apk add --no-cache \
+    bash \
+    build-base \
+    ca-certificates \
+    curl \
+    erlang \
+    erlang-dev \
+    git \
+    nodejs \
+    npm \
+    openssl-dev \
+    pkgconf \
+    tar \
+    xz
+
+# Install the Gleam compiler matching the architecture of this image.
+RUN set -eux; \
+    case "$TARGETARCH" in \
+      amd64) GLEAM_ARCH="x86_64-unknown-linux-musl" ;; \
+      arm64) GLEAM_ARCH="aarch64-unknown-linux-musl" ;; \
+      *) echo "Unsupported architecture: $TARGETARCH" >&2; exit 1 ;; \
+    esac; \
+    curl --fail --silent --show-error --location \
+      "https://github.com/gleam-lang/gleam/releases/download/v1.18.1/gleam-v1.18.1-${GLEAM_ARCH}.tar.gz" \
+      --output /tmp/gleam.tar.gz; \
+    tar -xzf /tmp/gleam.tar.gz -C /tmp; \
+    install -m 0755 /tmp/gleam /usr/local/bin/gleam; \
+    rm -rf /tmp/gleam /tmp/gleam.tar.gz
+
+ENV PATH="/root/.cargo/bin:/usr/local/bin:${PATH}"
+
+# Rust is used by Queso to compile its self-contained launcher.
+RUN curl --fail --silent --show-error https://sh.rustup.rs \
+      | sh -s -- -y --profile minimal \
+    && rustup default stable \
+    && rustup target add \
+      x86_64-unknown-linux-musl \
+      aarch64-unknown-linux-musl
+
+# Zig is used for the native cross-compilation and is installed for the
+# architecture running the builder.
+RUN set -eux; \
+    case "$TARGETARCH" in \
+      amd64) ZIG_ARCH="x86_64" ;; \
+      arm64) ZIG_ARCH="aarch64" ;; \
+      *) echo "Unsupported architecture: $TARGETARCH" >&2; exit 1 ;; \
+    esac; \
+    curl --fail --silent --show-error --location \
+      "https://ziglang.org/download/0.16.0/zig-${ZIG_ARCH}-linux-0.16.0.tar.xz" \
+      --output /tmp/zig.tar.xz; \
+    mkdir -p /opt/zig; \
+    tar -xJf /tmp/zig.tar.xz --strip-components=1 -C /opt/zig; \
+    ln -s /opt/zig/zig /usr/local/bin/zig; \
+    rm -f /tmp/zig.tar.xz
+
+RUN cargo install --locked queso \
+    && cargo install cargo-zigbuild
+
+RUN gleam --version \
+    && rustup --version \
+    && zig version \
+    && queso --version \
+    && cargo-zigbuild --version
+
+WORKDIR /build
+
+CMD ["gleam", "build"]
diff --git a/README.md b/README.md
index fe53400..0149117 100644
--- a/README.md
+++ b/README.md
@@ -104,6 +104,11 @@ does not need Erlang, Gleam, Zig, or Queso.
 ### CI artifacts
 
 Every push runs the native build in Gitea Actions after formatting succeeds.
+The binary build uses the prebuilt
+`jaypoch/luma-markdown-builder:latest` image, which contains Gleam, Rust,
+rustup, Zig, Queso, and `cargo-zigbuild`. The image definition is in
+[`Dockerfile.luma-builder`](Dockerfile.luma-builder).
+
 The workflow uploads two downloadable artifacts:
 
 - `luma_markdown-linux-x86_64`