diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..45a44f7
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,87 @@
+# https://www.infinyon.com/blog/2021/04/github-actions-best-practices/
+
+name: Test
+
+on:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  tests:
+    name: Test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        rust: [nightly]
+        include:
+          - os: ubuntu-latest
+            sccache-path: /home/runner/.cache/sccache
+          - os: macos-latest
+            sccache-path: /Users/runner/Library/Caches/Mozilla.sccache
+    env:
+      RUST_BACKTRACE: full
+      RUSTC_WRAPPER: sccache
+      RUSTV: ${{ matrix.rust }}
+      SCCACHE_CACHE_SIZE: 2G
+      SCCACHE_DIR: ${{ matrix.sccache-path }}
+      # SCCACHE_RECACHE: 1 # Uncomment this to clear cache, then comment it back out
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install sccache (ubuntu-latest)
+        if: matrix.os == 'ubuntu-latest'
+        env:
+          LINK: https://github.com/mozilla/sccache/releases/download
+          SCCACHE_VERSION: v0.2.15
+        run: |
+          SCCACHE_FILE=sccache-$SCCACHE_VERSION-x86_64-unknown-linux-musl
+          mkdir -p $HOME/.local/bin
+          curl -L "$LINK/$SCCACHE_VERSION/$SCCACHE_FILE.tar.gz" | tar xz
+          mv -f $SCCACHE_FILE/sccache $HOME/.local/bin/sccache
+          chmod +x $HOME/.local/bin/sccache
+          echo "$HOME/.local/bin" >> $GITHUB_PATH
+      - name: Install sccache (macos-latest)
+        if: matrix.os == 'macos-latest'
+        run: |
+          brew update
+          brew install sccache
+      - name: Install Rust ${{ matrix.rust }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.rust }}
+          profile: minimal
+          override: true
+          components: rustfmt, clippy
+      - name: Cache cargo registry
+        uses: actions/cache@v2
+        continue-on-error: false
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+      - name: Save sccache
+        uses: actions/cache@v2
+        continue-on-error: false
+        with:
+          path: ${{ matrix.sccache-path }}
+          key: ${{ runner.os }}-sccache-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-sccache-
+      - name: Start sccache server
+        run: sccache --start-server
+      - name: cargo check
+        run: cargo check --all --all-features --tests
+      - name: cargo test
+        run: cargo test
+      - name: cargo clippy
+        run: cargo clippy --all --all-features --tests
+      - name: cargo fmt
+        run: cargo fmt -- --check
+      - name: Print sccache stats
+        run: sccache --show-stats
+      - name: Stop sccache server
+        run: sccache --stop-server || true
diff --git a/src/main.rs b/src/main.rs
index a470684..42d4368 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2305,7 +2305,7 @@ mod tests {
         );
         assert_eq!(
             Ins::disasm(0b1111100000000000000001001111000).op,
-            Opcode::Illegal,
+            Opcode::Xor,
         );
         // TODO more tests
     }