diff --git a/src/firefox/ffBrowser.ts b/src/firefox/ffBrowser.ts
index 3756f52f28..cd97cde8f3 100644
--- a/src/firefox/ffBrowser.ts
+++ b/src/firefox/ffBrowser.ts
@@ -145,13 +145,11 @@ export class FFBrowser extends BrowserBase {
 export class FFBrowserContext extends BrowserContextBase {
   readonly _browser: FFBrowser;
   readonly _browserContextId: string | null;
-  private readonly _evaluateOnNewDocumentSources: string[];
 
   constructor(browser: FFBrowser, browserContextId: string | null, options: BrowserContextOptions) {
     super(browser, options);
     this._browser = browser;
     this._browserContextId = browserContextId;
-    this._evaluateOnNewDocumentSources = [];
     this._authenticateProxyViaHeader();
   }
 
@@ -304,7 +302,6 @@ export class FFBrowserContext extends BrowserContextBase {
 
   async addInitScript(script: Function | string | { path?: string, content?: string }, arg?: any) {
     const source = await helper.evaluationScript(script, arg);
-    this._evaluateOnNewDocumentSources.push(source);
     await this._browser._connection.send('Browser.addScriptToEvaluateOnNewDocument', { browserContextId: this._browserContextId || undefined, script: source });
   }
 
diff --git a/test/popup.spec.js b/test/popup.spec.js
index 9516dd8308..87db944cbe 100644
--- a/test/popup.spec.js
+++ b/test/popup.spec.js
@@ -174,7 +174,7 @@ describe('window.open', function() {
     expect(intercepted).toBe(true);
     await context.close();
   });
-  it('should apply addInitScript from browser context', async function({browser, server}) {
+  it('BrowserContext.addInitScript should apply to an in-process popup', async function({browser, server}) {
     const context = await browser.newContext();
     await context.addInitScript(() => window.injected = 123);
     const page = await context.newPage();
@@ -186,6 +186,21 @@ describe('window.open', function() {
     await context.close();
     expect(injected).toBe(123);
   });
+  it('BrowserContext.addInitScript should apply to a cross-process popup', async function({browser, server}) {
+    const context = await browser.newContext();
+    await context.addInitScript(() => window.injected = 123);
+    const page = await context.newPage();
+    await page.goto(server.EMPTY_PAGE);
+    const [popup] = await Promise.all([
+      page.waitForEvent('popup'),
+      page.evaluate(url => window.open(url), server.CROSS_PROCESS_PREFIX + '/title.html'),
+    ]);
+    expect(await popup.evaluate('injected')).toBe(123);
+    await popup.reload();
+    expect(await popup.evaluate('injected')).toBe(123);
+    await context.close();
+  });
+
   it('should expose function from browser context', async function({browser, server}) {
     const context = await browser.newContext();
     await context.exposeFunction('add', (a, b) => a + b);