diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b82bfcef1d..41308fe63e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -260,3 +260,52 @@ jobs:
       # when imported in an NPM node_modules tree.
       - name: Prepack packages
         run: yarn lerna run --reject-cycles --concurrency 1 prepack
+
+  test-xs:
+    name: test-xs
+
+    # begin macro
+
+    runs-on: ${{ matrix.platform }}
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [20.x]
+        xs-version: [5.0.0]
+        platform: [ubuntu-latest]
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      # without this, setup-node errors on mismatched yarn versions
+      - run: corepack enable
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: yarn
+
+      - name: Install dependencies
+        run: yarn install --immutable
+
+      # end macro
+
+      - name: Run yarn build
+        run: yarn build
+
+      - name: Clone XS
+        run: git clone https://github.com/moddable-OpenSource/moddable --branch "${{ matrix.xs-version }}" --depth 1
+
+      - name: Build XS
+        working-directory: moddable/xs/makefiles/lin
+        run: make debug MODDABLE=$GITHUB_WORKSPACE/moddable CC='cc "-D__has_builtin(x)=1"' # give the syntax highlighter a hand: '
+
+      - name: Is this thing on?
+        run: |
+          PATH=$PATH:$GITHUB_WORKSPACE/moddable/build/bin/lin/debug
+          xst -e true && ! xst -e null.reference
+
+      - name: Run XS tests
+        run: PATH=$PATH:$GITHUB_WORKSPACE/moddable/build/bin/lin/debug yarn lerna run test:xs