diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
index 7f4b3f6..1c41f09 100644
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@@ -33,26 +33,22 @@ jobs:
           path: psp-preserve-linux-x86_64.tar.gz
 
   windows:
-    name: Windows x64
+    name: Windows x64 (Wine)
     runs-on: windows
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/setup-python@v5
-        with:
-          python-version: "3.12"
-
       - name: Install build dependencies
         run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements-build.txt
+          winpython -m pip install --upgrade pip
+          winpython -m pip install -r requirements-build.txt
 
       - name: Build
-        run: pyinstaller --clean --noconfirm psp-preserve.spec
+        run: winpython -m PyInstaller --clean --noconfirm psp-preserve.spec
 
       - name: Package zip
-        shell: pwsh
-        run: Compress-Archive -Path dist\psp-preserve -DestinationPath psp-preserve-windows-x64.zip
+        run: |
+          cd dist && zip -rq ../psp-preserve-windows-x64.zip psp-preserve
 
       - uses: actions/upload-artifact@v4
         with:
diff --git a/README.md b/README.md
index c464f78..82b0a36 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,24 @@ act_runner.exe register \
 The registration token is generated in Gitea under
 **Site Administration → Actions → Runners → Create new runner**.
 
+#### Windows builds without a Windows box (Wine runner)
+
+The `windows` job targets a runner labelled `windows` that builds under Wine on
+Linux. Build it from `runner/`:
+
+```bash
+docker build -f runner/Dockerfile -t psp-wine-runner .
+docker run -d --name psp-wine-runner --restart unless-stopped \
+  -e GITEA_INSTANCE_URL=https://git.ceaf.dev \
+  -e GITEA_RUNNER_REGISTRATION_TOKEN=<registration-token> \
+  -v /mnt/user/appdata/psp-wine-runner:/data \
+  psp-wine-runner
+```
+
+The image ships Wine + Windows CPython 3.12 + PyInstaller, and registers itself
+with the `windows:host` label. (If you have a real Windows machine instead,
+register a native `act_runner.exe` with the same `windows` label.)
+
 ## First-time setup
 
 1. Put your DAT files in `data/dats/`:
diff --git a/runner/Dockerfile b/runner/Dockerfile
new file mode 100644
index 0000000..396acb8
--- /dev/null
+++ b/runner/Dockerfile
@@ -0,0 +1,52 @@
+# Wine-based Gitea Actions runner: builds Windows binaries on a Linux host.
+#
+# Jobs run in "host" mode inside this container, where a Windows CPython 3.12
+# (running under Wine) plus PyInstaller produce the .exe. Node.js and git are
+# included so the stock JS actions (actions/checkout, actions/upload-artifact)
+# work as-is.
+FROM debian:bookworm-slim
+
+ENV DEBIAN_FRONTEND=noninteractive \
+    WINEPREFIX=/root/.wine \
+    WINEDEBUG=-all \
+    WINEDLLOVERRIDES="mscoree,mshtml=" \
+    PYTHON_VERSION=3.12.8
+
+# Wine (64-bit), node + git for JS actions, and build/package tooling.
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates curl wget unzip zip \
+        wine wine64 xvfb winetricks cabextract \
+        nodejs git \
+    && apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Gitea Actions runner (linux-amd64 binary).
+RUN wget -qO /usr/local/bin/act_runner \
+      "https://gitea.com/gitea/act_runner/releases/download/v0.6.1/act_runner-0.6.1-linux-amd64" \
+    && chmod +x /usr/local/bin/act_runner
+
+# Windows CPython 3.12, silent install into C:\Python312.
+RUN wget -qO /tmp/python-installer.exe \
+      "https://www.python.org/ftp/python/${PYTHON_VERSION}/python-${PYTHON_VERSION}-amd64.exe" \
+    && xvfb-run -a wine /tmp/python-installer.exe \
+        /quiet InstallAllUsers=1 PrependPath=1 Include_test=0 Include_launcher=0 Shortcuts=0 \
+    && rm -f /tmp/python-installer.exe \
+    && wine "C:\\Python312\\python.exe" --version
+
+# MSVC runtime required by PySide6's Qt DLLs.
+RUN xvfb-run -a winetricks --unattended vcrun2022
+
+# Convenience wrapper: winpython -> wine C:\Python312\python.exe
+RUN printf '#!/bin/sh\nexec wine "C:\\Python312\\python.exe" "$@"\n' > /usr/local/bin/winpython \
+    && chmod +x /usr/local/bin/winpython
+
+# Pre-install the Windows build deps so CI jobs start fast.
+COPY requirements-build.txt /tmp/requirements-build.txt
+RUN winpython -m pip install --upgrade pip \
+    && winpython -m pip install -r /tmp/requirements-build.txt \
+    && rm -f /tmp/requirements-build.txt
+
+COPY runner/entrypoint.sh /usr/local/bin/entrypoint.sh
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+WORKDIR /data
+ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
diff --git a/runner/entrypoint.sh b/runner/entrypoint.sh
new file mode 100644
index 0000000..a8558fc
--- /dev/null
+++ b/runner/entrypoint.sh
@@ -0,0 +1,14 @@
+#!/bin/sh
+set -e
+
+# Register on first run, then run the daemon (host mode).
+if [ ! -f /data/.runner ]; then
+    echo "Registering Wine runner with Gitea…"
+    act_runner register --no-interactive \
+        --instance "${GITEA_INSTANCE_URL:?GITEA_INSTANCE_URL is required}" \
+        --token "${GITEA_RUNNER_REGISTRATION_TOKEN:?GITEA_RUNNER_REGISTRATION_TOKEN is required}" \
+        --name "${RUNNER_NAME:-windows-builder}" \
+        --labels "${RUNNER_LABELS:-windows:host}"
+fi
+
+exec act_runner daemon