diff --git a/packages/playwright/src/common/test.ts b/packages/playwright/src/common/test.ts
index a1afee5b08..578a1574f4 100644
--- a/packages/playwright/src/common/test.ts
+++ b/packages/playwright/src/common/test.ts
@@ -54,10 +54,12 @@ export class Suite extends Base implements SuitePrivate {
   _fullProject: FullProjectInternal | undefined;
   _fileId: string | undefined;
   readonly _type: 'root' | 'project' | 'file' | 'describe';
+  readonly _testTypeImpl: TestTypeImpl | undefined;
 
-  constructor(title: string, type: 'root' | 'project' | 'file' | 'describe') {
+  constructor(title: string, type: 'root' | 'project' | 'file' | 'describe', testTypeImpl?: TestTypeImpl) {
     super(title);
     this._type = type;
+    this._testTypeImpl = testTypeImpl;
   }
 
   get suites(): Suite[] {
diff --git a/packages/playwright/src/common/testType.ts b/packages/playwright/src/common/testType.ts
index 01d936f4d9..aba682f6dc 100644
--- a/packages/playwright/src/common/testType.ts
+++ b/packages/playwright/src/common/testType.ts
@@ -38,7 +38,7 @@ export class TestTypeImpl {
     test.only = wrapFunctionWithLocation(this._createTest.bind(this, 'only'));
     test.describe = wrapFunctionWithLocation(this._describe.bind(this, 'default'));
     test.describe.only = wrapFunctionWithLocation(this._describe.bind(this, 'only'));
-    test.describe.configure = wrapFunctionWithLocation(this._configure.bind(this));
+    test.describe.configure = this._configure.bind(this);
     test.describe.fixme = wrapFunctionWithLocation(this._describe.bind(this, 'fixme'));
     test.describe.parallel = wrapFunctionWithLocation(this._describe.bind(this, 'parallel'));
     test.describe.parallel.only = wrapFunctionWithLocation(this._describe.bind(this, 'parallel.only'));
@@ -53,7 +53,7 @@ export class TestTypeImpl {
     test.fixme = wrapFunctionWithLocation(this._modifier.bind(this, 'fixme'));
     test.fail = wrapFunctionWithLocation(this._modifier.bind(this, 'fail'));
     test.slow = wrapFunctionWithLocation(this._modifier.bind(this, 'slow'));
-    test.setTimeout = wrapFunctionWithLocation(this._setTimeout.bind(this));
+    test.setTimeout = this._setTimeout.bind(this);
     test.step = this._step.bind(this);
     test.use = wrapFunctionWithLocation(this._use.bind(this));
     test.extend = wrapFunctionWithLocation(this._extend.bind(this));
@@ -66,7 +66,7 @@ export class TestTypeImpl {
     this.test = test;
   }
 
-  private _currentSuite(location: Location, title: string): Suite | undefined {
+  private _currentSuite(title: string): Suite | undefined {
     const suite = currentlyLoadingFileSuite();
     if (!suite) {
       throw new Error([
@@ -78,12 +78,18 @@ export class TestTypeImpl {
         `  when one of the dependencies in your package.json depends on @playwright/test.`,
       ].join('\n'));
     }
+    if (suite._testTypeImpl && suite._testTypeImpl !== this) {
+      throw new Error([
+        `Can't call ${title} inside a describe() suite of a different test type.`,
+        `Make sure to use the same "test" function (created by the test.extend() call) for all declarations inside a suite.`,
+      ].join('\n'));
+    }
     return suite;
   }
 
   private _createTest(type: 'default' | 'only' | 'skip' | 'fixme' | 'fail', location: Location, title: string, fn: Function) {
     throwIfRunningInsideJest();
-    const suite = this._currentSuite(location, 'test()');
+    const suite = this._currentSuite('test()');
     if (!suite)
       return;
     const test = new TestCase(title, fn, this, location);
@@ -98,7 +104,7 @@ export class TestTypeImpl {
 
   private _describe(type: 'default' | 'only' | 'serial' | 'serial.only' | 'parallel' | 'parallel.only' | 'skip' | 'fixme', location: Location, title: string | Function, fn?: Function) {
     throwIfRunningInsideJest();
-    const suite = this._currentSuite(location, 'test.describe()');
+    const suite = this._currentSuite('test.describe()');
     if (!suite)
       return;
 
@@ -107,7 +113,7 @@ export class TestTypeImpl {
       title = '';
     }
 
-    const child = new Suite(title, 'describe');
+    const child = new Suite(title, 'describe', this);
     child._requireFile = suite._requireFile;
     child.location = location;
     suite._addSuite(child);
@@ -134,7 +140,7 @@ export class TestTypeImpl {
   }
 
   private _hook(name: 'beforeEach' | 'afterEach' | 'beforeAll' | 'afterAll', location: Location, title: string | Function, fn?: Function) {
-    const suite = this._currentSuite(location, `test.${name}()`);
+    const suite = this._currentSuite(`test.${name}()`);
     if (!suite)
       return;
     if (typeof title === 'function') {
@@ -145,9 +151,9 @@ export class TestTypeImpl {
     suite._hooks.push({ type: name, fn: fn!, title, location });
   }
 
-  private _configure(location: Location, options: { mode?: 'default' | 'parallel' | 'serial', retries?: number, timeout?: number }) {
+  private _configure(options: { mode?: 'default' | 'parallel' | 'serial', retries?: number, timeout?: number }) {
     throwIfRunningInsideJest();
-    const suite = this._currentSuite(location, `test.describe.configure()`);
+    const suite = this._currentSuite(`test.describe.configure()`);
     if (!suite)
       return;
 
@@ -198,7 +204,7 @@ export class TestTypeImpl {
     testInfo[type](...modifierArgs as [any, any]);
   }
 
-  private _setTimeout(location: Location, timeout: number) {
+  private _setTimeout(timeout: number) {
     const suite = currentlyLoadingFileSuite();
     if (suite) {
       suite._timeout = timeout;
@@ -212,7 +218,7 @@ export class TestTypeImpl {
   }
 
   private _use(location: Location, fixtures: Fixtures) {
-    const suite = this._currentSuite(location, `test.use()`);
+    const suite = this._currentSuite(`test.use()`);
     if (!suite)
       return;
     suite._use.push({ fixtures, location });
diff --git a/tests/playwright-test/basic.spec.ts b/tests/playwright-test/basic.spec.ts
index 3b47603c25..4c4b28ceeb 100644
--- a/tests/playwright-test/basic.spec.ts
+++ b/tests/playwright-test/basic.spec.ts
@@ -550,3 +550,22 @@ test('should support describe.fixme', async ({ runInlineTest }) => {
   expect(result.skipped).toBe(3);
   expect(result.output).toContain('heytest4');
 });
+
+test('should not allow mixing test types', async ({ runInlineTest }) => {
+  const result = await runInlineTest({
+    'mixed.spec.ts': `
+      import { test } from '@playwright/test';
+
+      export const test2 = test.extend({
+        value: 42,
+      });
+    
+      test.describe("test1 suite", () => {
+        test2("test 2", async () => {});
+      });
+    `
+  });
+  expect(result.exitCode).toBe(1);
+  expect(result.output).toContain(`Can't call test() inside a describe() suite of a different test type.`);
+  expect(result.output).toContain('>  9 |         test2(');
+});