diff --git a/packages/playwright-core/src/tools/mcp/config.ts b/packages/playwright-core/src/tools/mcp/config.ts
index f1994e4ea0a37..71c9fbd3d117c 100644
--- a/packages/playwright-core/src/tools/mcp/config.ts
+++ b/packages/playwright-core/src/tools/mcp/config.ts
@@ -212,7 +212,7 @@ async function validateBrowserConfig(browser: MergedConfig['browser']): Promise<
       browser.launchOptions.channel = 'chrome';
   }
 
-  if (browser.browserName === 'chromium' && browser.launchOptions.chromiumSandbox === undefined) {
+  if (browserName === 'chromium' && browser.launchOptions.chromiumSandbox === undefined) {
     if (process.platform === 'linux')
       browser.launchOptions.chromiumSandbox = browser.launchOptions.channel !== 'chromium' && browser.launchOptions.channel !== 'chrome-for-testing';
     else
diff --git a/tests/mcp/config-resolve.spec.ts b/tests/mcp/config-resolve.spec.ts
index d961bfec20465..9baadfa8b4231 100644
--- a/tests/mcp/config-resolve.spec.ts
+++ b/tests/mcp/config-resolve.spec.ts
@@ -107,6 +107,11 @@ test.describe('browserName and channel', () => {
 // ---------------------------------------------------------------------------
 
 test.describe('sandbox', () => {
+  test('chromium sandbox enabled by default', async () => {
+    const config = await resolveCLIConfigForMCP({}, emptyEnv);
+    expect(config.browser.launchOptions.chromiumSandbox).toBe(true);
+  });
+
   test('chromium sandbox enabled for chrome channel', async () => {
     const config = await resolveCLIConfigForMCP({ browser: 'chrome' }, emptyEnv);
     expect(config.browser.launchOptions.chromiumSandbox).toBe(true);