diff --git a/browser_patches/firefox-beta/BUILD_NUMBER b/browser_patches/firefox-beta/BUILD_NUMBER
index b867a00f2f..a3b3d6261f 100644
--- a/browser_patches/firefox-beta/BUILD_NUMBER
+++ b/browser_patches/firefox-beta/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1284
-Changed: lushnikov@chromium.org Wed 25 Aug 2021 08:50:22 AM PDT
+1285
+Changed: lushnikov@chromium.org Fri 27 Aug 2021 09:23:19 AM PDT
diff --git a/browser_patches/firefox-beta/juggler/content/PageAgent.js b/browser_patches/firefox-beta/juggler/content/PageAgent.js
index a007fdb853..234c6b0801 100644
--- a/browser_patches/firefox-beta/juggler/content/PageAgent.js
+++ b/browser_patches/firefox-beta/juggler/content/PageAgent.js
@@ -246,9 +246,9 @@ class PageAgent {
   }
 
   _filePickerShown(inputElement) {
-    if (inputElement.ownerGlobal.docShell !== this._docShell)
-      return;
     const frame = this._findFrameForNode(inputElement);
+    if (!frame)
+      return;
     this._browserPage.emit('pageFileChooserOpened', {
       executionContextId: frame.mainExecutionContext().id(),
       element: frame.mainExecutionContext().rawValueToRemoteObject(inputElement)
diff --git a/browser_patches/firefox/BUILD_NUMBER b/browser_patches/firefox/BUILD_NUMBER
index c7950901a1..bde0a84273 100644
--- a/browser_patches/firefox/BUILD_NUMBER
+++ b/browser_patches/firefox/BUILD_NUMBER
@@ -1,2 +1,2 @@
-1288
-Changed: joel.einbinder@gmail.com Wed 25 Aug 2021 08:41:36 AM PDT
+1289
+Changed: lushnikov@chromium.org Fri 27 Aug 2021 09:23:19 AM PDT
diff --git a/browser_patches/firefox/juggler/content/PageAgent.js b/browser_patches/firefox/juggler/content/PageAgent.js
index a007fdb853..234c6b0801 100644
--- a/browser_patches/firefox/juggler/content/PageAgent.js
+++ b/browser_patches/firefox/juggler/content/PageAgent.js
@@ -246,9 +246,9 @@ class PageAgent {
   }
 
   _filePickerShown(inputElement) {
-    if (inputElement.ownerGlobal.docShell !== this._docShell)
-      return;
     const frame = this._findFrameForNode(inputElement);
+    if (!frame)
+      return;
     this._browserPage.emit('pageFileChooserOpened', {
       executionContextId: frame.mainExecutionContext().id(),
       element: frame.mainExecutionContext().rawValueToRemoteObject(inputElement)
diff --git a/tests/page/page-set-input-files.spec.ts b/tests/page/page-set-input-files.spec.ts
index 66feef9aa2..5d2a8aba55 100644
--- a/tests/page/page-set-input-files.spec.ts
+++ b/tests/page/page-set-input-files.spec.ts
@@ -16,6 +16,7 @@
  */
 
 import { test as it, expect } from './pageTest';
+import { attachFrame } from '../config/utils';
 
 import path from 'path';
 import fs from 'fs';
@@ -69,6 +70,17 @@ it('should emit event once', async ({page, server}) => {
   expect(chooser).toBeTruthy();
 });
 
+it('should emit event for iframe', async ({page, server, browserName}) => {
+  it.skip(browserName === 'firefox');
+  const frame = await attachFrame(page, 'frame1', server.EMPTY_PAGE);
+  await frame.setContent(`<input type=file>`);
+  const [chooser] = await Promise.all([
+    new Promise(f => page.once('filechooser', f)),
+    frame.click('input'),
+  ]);
+  expect(chooser).toBeTruthy();
+});
+
 it('should emit event on/off', async ({page, server}) => {
   await page.setContent(`<input type=file>`);
   const [chooser] = await Promise.all([