diff --git a/packages/puppeteer-core/src/node/FirefoxLauncher.test.ts b/packages/puppeteer-core/src/node/FirefoxLauncher.test.ts
new file mode 100644
index 00000000000..ec11967dec8
--- /dev/null
+++ b/packages/puppeteer-core/src/node/FirefoxLauncher.test.ts
@@ -0,0 +1,57 @@
+/**
+ * Copyright 2023 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {describe, it} from 'node:test';
+
+import expect from 'expect';
+
+import {FirefoxLauncher} from './FirefoxLauncher.js';
+
+describe('FirefoxLauncher', function () {
+  describe('getPreferences', function () {
+    it('should return preferences for CDP', async () => {
+      const prefs: Record<string, unknown> = FirefoxLauncher.getPreferences(
+        {
+          test: 1,
+        },
+        undefined
+      );
+      expect(prefs['test']).toBe(1);
+      expect(prefs['fission.bfcacheInParent']).toBe(false);
+      expect(prefs['fission.webContentIsolationStrategy']).toBe(0);
+      expect(prefs).toEqual(
+        FirefoxLauncher.getPreferences(
+          {
+            test: 1,
+          },
+          'cdp'
+        )
+      );
+    });
+
+    it('should return preferences for WebDriver BiDi', async () => {
+      const prefs: Record<string, unknown> = FirefoxLauncher.getPreferences(
+        {
+          test: 1,
+        },
+        'webDriverBiDi'
+      );
+      expect(prefs['test']).toBe(1);
+      expect(prefs['fission.bfcacheInParent']).toBe(undefined);
+      expect(prefs['fission.webContentIsolationStrategy']).toBe(0);
+    });
+  });
+});
diff --git a/packages/puppeteer-core/src/node/FirefoxLauncher.ts b/packages/puppeteer-core/src/node/FirefoxLauncher.ts
index cd610d24516..f91f613fe74 100644
--- a/packages/puppeteer-core/src/node/FirefoxLauncher.ts
+++ b/packages/puppeteer-core/src/node/FirefoxLauncher.ts
@@ -45,6 +45,28 @@ export class FirefoxLauncher extends ProductLauncher {
   constructor(puppeteer: PuppeteerNode) {
     super(puppeteer, 'firefox');
   }
+
+  static getPreferences(
+    extraPrefsFirefox?: Record<string, unknown>,
+    protocol?: 'cdp' | 'webDriverBiDi'
+  ): Record<string, unknown> {
+    return {
+      ...extraPrefsFirefox,
+      ...(protocol === 'webDriverBiDi'
+        ? {}
+        : {
+            // Temporarily force disable BFCache in parent (https://bit.ly/bug-1732263)
+            'fission.bfcacheInParent': false,
+          }),
+      // Force all web content to use a single content process. TODO: remove
+      // this once Firefox supports mouse event dispatch from the main frame
+      // context. Once this happens, webContentIsolationStrategy should only
+      // be set for CDP. See
+      // https://bugzilla.mozilla.org/show_bug.cgi?id=1773393
+      'fission.webContentIsolationStrategy': 0,
+    };
+  }
+
   /**
    * @internal
    */
@@ -113,21 +135,10 @@ export class FirefoxLauncher extends ProductLauncher {
 
     await createProfile(SupportedBrowsers.FIREFOX, {
       path: userDataDir,
-      preferences: {
-        ...extraPrefsFirefox,
-        ...(options.protocol === 'cdp'
-          ? {
-              // Temporarily force disable BFCache in parent (https://bit.ly/bug-1732263)
-              'fission.bfcacheInParent': false,
-            }
-          : {}),
-        // Force all web content to use a single content process. TODO: remove
-        // this once Firefox supports mouse event dispatch from the main frame
-        // context. Once this happens, webContentIsolationStrategy should only
-        // be set for CDP. See
-        // https://bugzilla.mozilla.org/show_bug.cgi?id=1773393
-        'fission.webContentIsolationStrategy': 0,
-      },
+      preferences: FirefoxLauncher.getPreferences(
+        extraPrefsFirefox,
+        options.protocol
+      ),
     });
 
     let firefoxExecutable: string;