diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..b522e24
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,21 @@
+name: CI
+on: push
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build # I.e., verify that it compiles.
+        run: |
+          . run.sh
+          run::build
+      - name: Run tests
+        run: |
+          . run.sh
+          run::test
+      - name: Check formatting
+        run: |
+          . run.sh
+          run::format
+          [[ "$(git status --porcelain)" ]] && git status && exit 1