diff --git a/packages/playwright-cloudflare/index.d.ts b/packages/playwright-cloudflare/index.d.ts
index 35f8ddd97..bc7691f07 100644
--- a/packages/playwright-cloudflare/index.d.ts
+++ b/packages/playwright-cloudflare/index.d.ts
@@ -3,6 +3,17 @@ import { Playwright, Browser } from './types/types';
 
 export * from './types/types';
 
+declare module './types/types' {
+  interface Browser {
+    /**
+     * Get the BISO session ID associated with this browser
+     *
+     * @public
+     */
+    sessionId(): string;
+  }
+}
+
 /**
  * @public
  */
diff --git a/packages/playwright-cloudflare/src/cloudflare/webSocketTransport.ts b/packages/playwright-cloudflare/src/cloudflare/webSocketTransport.ts
index bedfc584e..a4daf13d8 100644
--- a/packages/playwright-cloudflare/src/cloudflare/webSocketTransport.ts
+++ b/packages/playwright-cloudflare/src/cloudflare/webSocketTransport.ts
@@ -7,13 +7,13 @@ import { AsyncLocalStorage } from 'async_hooks';
 export const transportZone = new AsyncLocalStorage<WebSocketTransport>();
 
 export class WebSocketTransport implements ConnectionTransport {
-  ws: WebSocket;
-  pingInterval: NodeJS.Timer;
-  chunks: Uint8Array[] = [];
+  private _ws: WebSocket;
+  private _pingInterval: NodeJS.Timer;
+  private _chunks: Uint8Array[] = [];
   onmessage?: (message: ProtocolResponse) => void;
   onclose?: () => void;
-  sessionId: string;
-  
+  readonly sessionId: string;
+
   static async connect(): Promise<WebSocketTransport> {
     // read the endpoint and options injected in cliend side
     const transport = transportZone.getStore();
@@ -23,42 +23,42 @@ export class WebSocketTransport implements ConnectionTransport {
   }
 
   constructor(ws: WebSocket, sessionId: string) {
-    this.pingInterval = setInterval(() => {
-      return this.ws.send('ping');
+    this._pingInterval = setInterval(() => {
+      return this._ws.send('ping');
     }, 1000); // TODO more investigation
-    this.ws = ws;
+    this._ws = ws;
     this.sessionId = sessionId;
-    this.ws.addEventListener('message', event => {
-      this.chunks.push(new Uint8Array(event.data as ArrayBuffer));
-      const message = chunksToMessage(this.chunks, sessionId);
+    this._ws.addEventListener('message', event => {
+      this._chunks.push(new Uint8Array(event.data as ArrayBuffer));
+      const message = chunksToMessage(this._chunks, sessionId);
       if (message && this.onmessage)
         this.onmessage!(JSON.parse(message) as ProtocolResponse);
     });
-    this.ws.addEventListener('close', () => {
-      clearInterval(this.pingInterval as NodeJS.Timeout);
+    this._ws.addEventListener('close', () => {
+      clearInterval(this._pingInterval as NodeJS.Timeout);
       if (this.onclose)
         this.onclose();
     });
-    this.ws.addEventListener('error', e => {
+    this._ws.addEventListener('error', e => {
       // eslint-disable-next-line no-console
       console.error(`Websocket error: SessionID: ${sessionId}`, e);
-      clearInterval(this.pingInterval as NodeJS.Timeout);
+      clearInterval(this._pingInterval as NodeJS.Timeout);
     });
   }
 
   send(message: ProtocolRequest): void {
     for (const chunk of messageToChunks(JSON.stringify(message)))
-      this.ws.send(chunk);
+      this._ws.send(chunk);
   }
 
   close(): void {
-    clearInterval(this.pingInterval as NodeJS.Timeout);
-    this.ws.close();
+    clearInterval(this._pingInterval as NodeJS.Timeout);
+    this._ws.close();
     this.onclose?.();
   }
 
   async closeAndWait() {
-    if (this.ws.readyState === WebSocket.CLOSED)
+    if (this._ws.readyState === WebSocket.CLOSED)
       return;
     this.close();
     // TODO wait for close event
diff --git a/packages/playwright-cloudflare/src/index.ts b/packages/playwright-cloudflare/src/index.ts
index e75bab977..c7d57974a 100644
--- a/packages/playwright-cloudflare/src/index.ts
+++ b/packages/playwright-cloudflare/src/index.ts
@@ -8,7 +8,6 @@ import type { AcquireResponse, ActiveSession, Browser, BrowserWorker, ClosedSess
 import { transportZone, WebSocketTransport } from './cloudflare/webSocketTransport';
 import { wrapClientApis } from './cloudflare/wrapClientApis';
 import { kBrowserCloseMessageId } from 'playwright-core/lib/server/chromium/crConnection';
-import { isUnderTest } from 'playwright-core/lib/utils';
 
 const playwright = createInProcessPlaywright();
 wrapClientApis();
@@ -17,7 +16,11 @@ const HTTP_FAKE_HOST = 'http://fake.host';
 const WS_FAKE_HOST = 'ws://fake.host';
 
 async function createBrowser(transport: WebSocketTransport): Promise<Browser> {
-  return await transportZone.run(transport, async () => await playwright.chromium.connectOverCDP(WS_FAKE_HOST) as Browser);
+  return await transportZone.run(transport, async () => {
+    const browser = await playwright.chromium.connectOverCDP(WS_FAKE_HOST) as Browser;
+    browser.sessionId = () => transport.sessionId;
+    return browser;
+  });
 }
 
 export async function connect(endpoint: BrowserWorker, sessionId: string): Promise<Browser> {
@@ -34,9 +37,6 @@ export async function launch(endpoint: BrowserWorker, options?: WorkersLaunchOpt
   // keeps the endpoint and options for client -> server async communication
   const browser = await createBrowser(transport) as Browser;
 
-  if (isUnderTest())
-    (browser as any).__sessionIdForTest = sessionId;
-
   const browserImpl = (browser as any)._toImpl() as CRBrowser;
   // ensure we actually close the browser
   const doClose = async () => {
diff --git a/packages/playwright-cloudflare/tests/src/browser-rendering/api.spec.ts b/packages/playwright-cloudflare/tests/src/browser-rendering/api.spec.ts
index f7f8eb344..ee6e060af 100644
--- a/packages/playwright-cloudflare/tests/src/browser-rendering/api.spec.ts
+++ b/packages/playwright-cloudflare/tests/src/browser-rendering/api.spec.ts
@@ -3,7 +3,7 @@ import { launch, connect, sessions, BrowserWorker, Browser, history, acquire } f
 
 async function launchAndGetSession(endpoint: BrowserWorker): Promise<[Browser, string]> {
   const browser = await launch(endpoint);
-  const sessionId = (browser as any).__sessionIdForTest;
+  const sessionId = browser.sessionId();
   expect(sessionId).toBeDefined();
   return [browser, sessionId];
 }