diff --git a/.gitattributes b/.gitattributes
index 478a2db..cb1b6e5 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -8,3 +8,4 @@
 /*.lock  export-ignore
 /*.dist  export-ignore
 /*.php   export-ignore
+/infection.json5 export-ignore
diff --git a/.github/workflows/mutation.yml b/.github/workflows/mutation.yml
new file mode 100644
index 0000000..9484c92
--- /dev/null
+++ b/.github/workflows/mutation.yml
@@ -0,0 +1,51 @@
+---
+
+name: Mutation Tests
+
+on:  # yamllint disable-line rule:truthy
+  pull_request:
+  push:
+    branches: [2.x]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  mutation:
+    name: Infection
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.4'
+          coverage: xdebug
+          ini-values: memory_limit=-1
+
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@v3
+        with:
+          dependency-versions: highest
+
+      # The Infection phar is unusable with Testo: its bundled adapter calls the
+      # unscoped \Infection\StreamWrapper\IncludeInterceptor. Infection requires
+      # PHP 8.3+, so it is installed here instead of in require-dev.
+      - name: Install Infection
+        run: |
+          composer config allow-plugins.infection/extension-installer true
+          composer require --dev --no-interaction --no-progress -W infection/infection testo/bridge-infection
+
+      - name: Run Infection
+        run: vendor/bin/infection --threads=max --logger-github --show-mutations=0 --min-msi=60 --min-covered-msi=60
+        env:
+          STRYKER_DASHBOARD_API_KEY: ${{ github.event_name == 'push' && secrets.STRYKER_DASHBOARD_API_KEY || '' }}
diff --git a/README.md b/README.md
index 7f04bb4..fcf4bb9 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,7 @@
 
 [![Psalm Level](https://shepherd.dev/github/roadrunner-php/cli/level.svg)](https://shepherd.dev/github/roadrunner-php/cli)
 [![Type Coverage](https://shepherd.dev/github/roadrunner-php/cli/coverage.svg)](https://shepherd.dev/github/roadrunner-php/cli)
+[![Mutation testing badge](https://img.shields.io/endpoint?style=flat&url=https%3A%2F%2Fbadge-api.stryker-mutator.io%2Fgithub.com%2Froadrunner-php%2Fcli%2F2.x)](https://dashboard.stryker-mutator.io/reports/github.com/roadrunner-php/cli/2.x)
 
 </div>
 
diff --git a/infection.json5 b/infection.json5
new file mode 100644
index 0000000..b6307ae
--- /dev/null
+++ b/infection.json5
@@ -0,0 +1,16 @@
+{
+    "$schema": "https://raw.githubusercontent.com/infection/infection/0.35.6/resources/schema.json",
+    "source": {
+        "directories": ["src"]
+    },
+    "testFramework": "testo",
+    "tmpDir": "runtime",
+    "timeout": 10,
+    "logs": {
+        "text": "runtime/infection.log",
+        "github": true,
+        "stryker": {
+            "report": "2.x"
+        }
+    }
+}
diff --git a/tests/Unit/GetBinaryCommandTest.php b/tests/Unit/GetBinaryCommandTest.php
index 02fae4a..779a89a 100644
--- a/tests/Unit/GetBinaryCommandTest.php
+++ b/tests/Unit/GetBinaryCommandTest.php
@@ -29,17 +29,26 @@ final class GetBinaryCommandTest
     /** @var list<string> */
     private array $downloads = [];
 
+    private string $cwd;
+
+    /**
+     * The command also looks for ".rr.yaml" in the working directory, so each test gets its own.
+     */
     #[BeforeTest]
     public function createDirectory(): void
     {
         $this->dir = TempDirectory::create();
         $this->target = $this->dir . '/bin';
         \mkdir($this->target);
+        $this->cwd = (string) \getcwd();
+        \mkdir($this->dir . '/cwd');
+        \chdir($this->dir . '/cwd');
     }
 
     #[AfterTest]
     public function removeDirectory(): void
     {
+        \chdir($this->cwd);
         TempDirectory::remove($this->dir);
     }
 
diff --git a/tests/Unit/MakeConfigCommandTest.php b/tests/Unit/MakeConfigCommandTest.php
index 435d991..5255dd5 100644
--- a/tests/Unit/MakeConfigCommandTest.php
+++ b/tests/Unit/MakeConfigCommandTest.php
@@ -18,16 +18,24 @@
 final class MakeConfigCommandTest
 {
     private string $dir;
+    private string $cwd;
 
+    /**
+     * The command also looks for ".rr.yaml" in the working directory, so each test gets its own.
+     */
     #[BeforeTest]
     public function createDirectory(): void
     {
         $this->dir = TempDirectory::create();
+        $this->cwd = (string) \getcwd();
+        \mkdir($this->dir . '/cwd');
+        \chdir($this->dir . '/cwd');
     }
 
     #[AfterTest]
     public function removeDirectory(): void
     {
+        \chdir($this->cwd);
         TempDirectory::remove($this->dir);
     }
 
@@ -74,6 +82,16 @@ public function keepsExistingConfiguration(): void
         Assert::same(\file_get_contents($this->dir . '/.rr.yaml'), 'existing');
     }
 
+    public function keepsConfigurationOfWorkingDirectory(): void
+    {
+        \file_put_contents($this->dir . '/cwd/.rr.yaml', 'existing');
+
+        $status = $this->run(['--location' => $this->dir]);
+
+        Assert::same($status, Command::FAILURE);
+        Assert::false(\is_file($this->dir . '/.rr.yaml'));
+    }
+
     /**
      * @param array<string, mixed> $input
      */