diff --git a/packages/playwright-core/src/server/browserContext.ts b/packages/playwright-core/src/server/browserContext.ts
index c8d54471ee..d952c9aa94 100644
--- a/packages/playwright-core/src/server/browserContext.ts
+++ b/packages/playwright-core/src/server/browserContext.ts
@@ -588,7 +588,7 @@ export function assertBrowserContextIsNotOwned(context: BrowserContext) {
 export function validateBrowserContextOptions(options: channels.BrowserNewContextParams, browserOptions: BrowserOptions) {
   if (options.noDefaultViewport && options.deviceScaleFactor !== undefined)
     throw new Error(`"deviceScaleFactor" option is not supported with null "viewport"`);
-  if (options.noDefaultViewport && options.isMobile !== undefined)
+  if (options.noDefaultViewport && !!options.isMobile)
     throw new Error(`"isMobile" option is not supported with null "viewport"`);
   if (options.acceptDownloads === undefined)
     options.acceptDownloads = true;
diff --git a/packages/playwright-test/src/index.ts b/packages/playwright-test/src/index.ts
index b76917c425..5685cd0272 100644
--- a/packages/playwright-test/src/index.ts
+++ b/packages/playwright-test/src/index.ts
@@ -127,18 +127,18 @@ const playwrightFixtures: Fixtures<TestFixtures, WorkerFixtures> = ({
   }, { scope: 'worker', timeout: 0 }],
 
   acceptDownloads: [({ contextOptions }, use) => use(contextOptions.acceptDownloads ?? true), { option: true }],
-  bypassCSP: [({ contextOptions }, use) => use(contextOptions.bypassCSP), { option: true }],
-  colorScheme: [({ contextOptions }, use) => use(contextOptions.colorScheme), { option: true }],
+  bypassCSP: [({ contextOptions }, use) => use(contextOptions.bypassCSP ?? false), { option: true }],
+  colorScheme: [({ contextOptions }, use) => use(contextOptions.colorScheme === undefined ? 'light' : contextOptions.colorScheme), { option: true }],
   deviceScaleFactor: [({ contextOptions }, use) => use(contextOptions.deviceScaleFactor), { option: true }],
   extraHTTPHeaders: [({ contextOptions }, use) => use(contextOptions.extraHTTPHeaders), { option: true }],
   geolocation: [({ contextOptions }, use) => use(contextOptions.geolocation), { option: true }],
-  hasTouch: [({ contextOptions }, use) => use(contextOptions.hasTouch), { option: true }],
+  hasTouch: [({ contextOptions }, use) => use(contextOptions.hasTouch ?? false), { option: true }],
   httpCredentials: [({ contextOptions }, use) => use(contextOptions.httpCredentials), { option: true }],
-  ignoreHTTPSErrors: [({ contextOptions }, use) => use(contextOptions.ignoreHTTPSErrors), { option: true }],
-  isMobile: [({ contextOptions }, use) => use(contextOptions.isMobile), { option: true }],
+  ignoreHTTPSErrors: [({ contextOptions }, use) => use(contextOptions.ignoreHTTPSErrors ?? false), { option: true }],
+  isMobile: [({ contextOptions }, use) => use(contextOptions.isMobile ?? false), { option: true }],
   javaScriptEnabled: [({ contextOptions }, use) => use(contextOptions.javaScriptEnabled ?? true), { option: true }],
   locale: [({ contextOptions }, use) => use(contextOptions.locale ?? 'en-US'), { option: true }],
-  offline: [({ contextOptions }, use) => use(contextOptions.offline), { option: true }],
+  offline: [({ contextOptions }, use) => use(contextOptions.offline ?? false), { option: true }],
   permissions: [({ contextOptions }, use) => use(contextOptions.permissions), { option: true }],
   proxy: [({ contextOptions }, use) => use(contextOptions.proxy), { option: true }],
   storageState: [({ contextOptions }, use) => use(contextOptions.storageState), { option: true }],
diff --git a/packages/playwright-test/types/test.d.ts b/packages/playwright-test/types/test.d.ts
index 6afe389f07..650b8439c4 100644
--- a/packages/playwright-test/types/test.d.ts
+++ b/packages/playwright-test/types/test.d.ts
@@ -3362,7 +3362,7 @@ export interface PlaywrightWorkerOptions {
    * [Firefox](https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Headless_mode). Defaults to `true` unless the
    * `devtools` option is `true`.
    */
-  headless: boolean | undefined;
+  headless: boolean;
   /**
    * Browser distribution channel.  Supported values are "chrome", "chrome-beta", "chrome-dev", "chrome-canary",
    * "msedge", "msedge-beta", "msedge-dev", "msedge-canary". Read more about using
@@ -3468,17 +3468,17 @@ export interface PlaywrightTestOptions {
   /**
    * Whether to automatically download all the attachments. Defaults to `true` where all the downloads are accepted.
    */
-  acceptDownloads: boolean | undefined;
+  acceptDownloads: boolean;
   /**
    * Toggles bypassing page's Content-Security-Policy.
    */
-  bypassCSP: boolean | undefined;
+  bypassCSP: boolean;
   /**
    * Emulates `'prefers-colors-scheme'` media feature, supported values are `'light'`, `'dark'`, `'no-preference'`. See
    * [page.emulateMedia([options])](https://playwright.dev/docs/api/class-page#page-emulate-media) for more details.
    * Passing `null` resets emulation to system defaults. Defaults to `'light'`.
    */
-  colorScheme: ColorScheme | undefined;
+  colorScheme: ColorScheme;
   /**
    * Specify device scale factor (can be thought of as dpr). Defaults to `1`.
    */
@@ -3491,7 +3491,7 @@ export interface PlaywrightTestOptions {
   /**
    * Specifies if viewport supports touch events. Defaults to false.
    */
-  hasTouch: boolean | undefined;
+  hasTouch: boolean;
   /**
    * Credentials for [HTTP authentication](https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication).
    */
@@ -3499,16 +3499,16 @@ export interface PlaywrightTestOptions {
   /**
    * Whether to ignore HTTPS errors when sending network requests. Defaults to `false`.
    */
-  ignoreHTTPSErrors: boolean | undefined;
+  ignoreHTTPSErrors: boolean;
   /**
    * Whether the `meta viewport` tag is taken into account and touch events are enabled. Defaults to `false`. Not
    * supported in Firefox.
    */
-  isMobile: boolean | undefined;
+  isMobile: boolean;
   /**
    * Whether or not to enable JavaScript in the context. Defaults to `true`.
    */
-  javaScriptEnabled: boolean | undefined;
+  javaScriptEnabled: boolean;
   /**
    * Specify user locale, for example `en-GB`, `de-DE`, etc. Locale will affect `navigator.language` value,
    * `Accept-Language` request header value as well as number and date formatting rules.
@@ -3517,7 +3517,7 @@ export interface PlaywrightTestOptions {
   /**
    * Whether to emulate network being offline. Defaults to `false`.
    */
-  offline: boolean | undefined;
+  offline: boolean;
   /**
    * A list of permissions to grant to all pages in this context. See
    * [browserContext.grantPermissions(permissions[, options])](https://playwright.dev/docs/api/class-browsercontext#browser-context-grant-permissions)
@@ -3552,7 +3552,7 @@ export interface PlaywrightTestOptions {
    * **NOTE** The `null` value opts out from the default presets, makes viewport depend on the host window size defined
    * by the operating system. It makes the execution of the tests non-deterministic.
    */
-  viewport: ViewportSize | null | undefined;
+  viewport: ViewportSize | null;
   /**
    * When using [page.goto(url[, options])](https://playwright.dev/docs/api/class-page#page-goto),
    * [page.route(url, handler[, options])](https://playwright.dev/docs/api/class-page#page-route),
@@ -3585,7 +3585,7 @@ export interface PlaywrightTestOptions {
    *
    * Learn more about [various timeouts](https://playwright.dev/docs/test-timeouts).
    */
-  actionTimeout: number | undefined;
+  actionTimeout: number;
   /**
    * Timeout for each navigation action in milliseconds. Defaults to 0 (no timeout).
    *
@@ -3594,20 +3594,20 @@ export interface PlaywrightTestOptions {
    *
    * Learn more about [various timeouts](https://playwright.dev/docs/test-timeouts).
    */
-  navigationTimeout: number | undefined;
+  navigationTimeout: number;
   /**
    * Whether to allow sites to register Service workers. Defaults to `'allow'`.
    * - `'allow'`: [Service Workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API) can be
    *   registered.
    * - `'block'`: Playwright will block all registration of Service Workers.
    */
-  serviceWorkers: ServiceWorkerPolicy | undefined;
+  serviceWorkers: ServiceWorkerPolicy;
   /**
    * Custom attribute to be used in
    * [page.getByTestId(testId)](https://playwright.dev/docs/api/class-page#page-get-by-test-id). `data-testid` is used
    * by default.
    */
-  testIdAttribute: string | undefined;
+  testIdAttribute: string;
 }
 
 
diff --git a/tests/playwright-test/playwright.spec.ts b/tests/playwright-test/playwright.spec.ts
index 026af19372..cf42ae1613 100644
--- a/tests/playwright-test/playwright.spec.ts
+++ b/tests/playwright-test/playwright.spec.ts
@@ -686,3 +686,65 @@ test('should not throw with many fixtures set to undefined', async ({ runInlineT
   expect(result.exitCode).toBe(0);
   expect(result.passed).toBe(1);
 });
+
+test('should have strict types for options but allow use(undefined)', async ({ runTSC }) => {
+  const result = await runTSC({
+    'a.spec.ts': `
+      const { test } = pwt;
+      test.use({
+        headless: undefined,
+        acceptDownloads: undefined,
+        bypassCSP: undefined,
+        hasTouch: undefined,
+        ignoreHTTPSErrors: undefined,
+        isMobile: undefined,
+        javaScriptEnabled: undefined,
+        offline: undefined,
+        actionTimeout: undefined,
+        navigationTimeout: undefined,
+        testIdAttribute: undefined,
+      });
+      test('my test', async ({
+          headless, acceptDownloads, bypassCSP,
+          hasTouch, ignoreHTTPSErrors, isMobile, javaScriptEnabled, offline,
+          actionTimeout, navigationTimeout, testIdAttribute }) => {
+        test.skip(headless, 'boolean');
+        test.skip(acceptDownloads, 'boolean');
+        test.skip(bypassCSP, 'boolean');
+        test.skip(hasTouch, 'boolean');
+        test.skip(ignoreHTTPSErrors, 'boolean');
+        test.skip(isMobile, 'boolean');
+        test.skip(javaScriptEnabled, 'boolean');
+        test.skip(offline, 'boolean');
+        test.skip(actionTimeout > 0, 'number');
+        test.skip(navigationTimeout > 0, 'number');
+        test.skip(testIdAttribute.length > 0, 'string');
+      });
+    `,
+  });
+  expect(result.exitCode).toBe(0);
+});
+
+test('should skip on mobile', async ({ runInlineTest }) => {
+  const result = await runInlineTest({
+    'a.spec.ts': `
+      const { test } = pwt;
+
+      test.describe(() => {
+        test.use({ isMobile: true });
+        test('test 1', async ({ isMobile }) => {
+          test.skip(isMobile, 'desktop only!');
+        });
+      });
+
+      test.describe(() => {
+        test('test 2', async ({ isMobile }) => {
+          test.skip(isMobile, 'desktop only!');
+        });
+      });
+    `,
+  });
+  expect(result.exitCode).toBe(0);
+  expect(result.skipped).toBe(1);
+  expect(result.passed).toBe(1);
+});
diff --git a/utils/generate_types/overrides-test.d.ts b/utils/generate_types/overrides-test.d.ts
index ef765b698b..8635cc6a11 100644
--- a/utils/generate_types/overrides-test.d.ts
+++ b/utils/generate_types/overrides-test.d.ts
@@ -200,7 +200,7 @@ type ConnectOptions = {
 export interface PlaywrightWorkerOptions {
   browserName: BrowserName;
   defaultBrowserType: BrowserName;
-  headless: boolean | undefined;
+  headless: boolean;
   channel: BrowserChannel | undefined;
   launchOptions: LaunchOptions;
   connectOptions: ConnectOptions | undefined;
@@ -214,31 +214,31 @@ export type TraceMode = 'off' | 'on' | 'retain-on-failure' | 'on-first-retry';
 export type VideoMode = 'off' | 'on' | 'retain-on-failure' | 'on-first-retry';
 
 export interface PlaywrightTestOptions {
-  acceptDownloads: boolean | undefined;
-  bypassCSP: boolean | undefined;
-  colorScheme: ColorScheme | undefined;
+  acceptDownloads: boolean;
+  bypassCSP: boolean;
+  colorScheme: ColorScheme;
   deviceScaleFactor: number | undefined;
   extraHTTPHeaders: ExtraHTTPHeaders | undefined;
   geolocation: Geolocation | undefined;
-  hasTouch: boolean | undefined;
+  hasTouch: boolean;
   httpCredentials: HTTPCredentials | undefined;
-  ignoreHTTPSErrors: boolean | undefined;
-  isMobile: boolean | undefined;
-  javaScriptEnabled: boolean | undefined;
+  ignoreHTTPSErrors: boolean;
+  isMobile: boolean;
+  javaScriptEnabled: boolean;
   locale: string | undefined;
-  offline: boolean | undefined;
+  offline: boolean;
   permissions: string[] | undefined;
   proxy: Proxy | undefined;
   storageState: StorageState | undefined;
   timezoneId: string | undefined;
   userAgent: string | undefined;
-  viewport: ViewportSize | null | undefined;
+  viewport: ViewportSize | null;
   baseURL: string | undefined;
   contextOptions: BrowserContextOptions;
-  actionTimeout: number | undefined;
-  navigationTimeout: number | undefined;
-  serviceWorkers: ServiceWorkerPolicy | undefined;
-  testIdAttribute: string | undefined;
+  actionTimeout: number;
+  navigationTimeout: number;
+  serviceWorkers: ServiceWorkerPolicy;
+  testIdAttribute: string;
 }