diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..cca26cba
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,40 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+# Cancel in-flight runs for the same ref when new commits land.
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  check:
+    name: fmt, clippy, test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Format
+        run: cargo fmt --all --check
+
+      - name: Clippy
+        run: cargo clippy --all-targets -- -D warnings
+
+      - name: Build
+        run: cargo build --locked
+
+      - name: Test
+        run: cargo test --locked
diff --git a/src/commands/chart.rs b/src/commands/chart.rs
index bd41169a..cb8d9839 100644
--- a/src/commands/chart.rs
+++ b/src/commands/chart.rs
@@ -250,7 +250,7 @@ mod tests {
         assert_eq!(fmt(99999.0), "1.000e+5");
         assert_eq!(fmt(0.0001234), "1.234e-4");
         // ordinary values
-        assert_eq!(fmt(3.14159), "3.142");
+        assert_eq!(fmt(3.21459), "3.215");
         assert_eq!(fmt(-42.0), "-42.00");
     }
 }