diff --git a/py/BUILD.bazel b/py/BUILD.bazel
index ea7b0dd374692..322ae35d51c70 100644
--- a/py/BUILD.bazel
+++ b/py/BUILD.bazel
@@ -363,7 +363,6 @@ py_library(
         "test/selenium/webdriver/common/network.py",
         "test/selenium/webdriver/common/webserver.py",
         "test/selenium/webdriver/firefox/__init__.py",
-        "test/selenium/webdriver/firefox/conftest.py",
         "test/selenium/webdriver/marionette/__init__.py",
         "test/selenium/webdriver/marionette/conftest.py",
         "test/selenium/webdriver/safari/conftest.py",
diff --git a/py/conftest.py b/py/conftest.py
index 555ec7b0f0505..5f21cac98e955 100644
--- a/py/conftest.py
+++ b/py/conftest.py
@@ -467,6 +467,7 @@ def clean_driver(request):
         pytest.xfail(**marker.kwargs)
 
     yield driver_reference
+
     if request.node.get_closest_marker("no_driver_after_test"):
         driver_reference = None
 
diff --git a/py/pyproject.toml b/py/pyproject.toml
index 3b8bd059d6337..c2d5eeeed37a2 100644
--- a/py/pyproject.toml
+++ b/py/pyproject.toml
@@ -24,7 +24,7 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
-    ]
+]
 dependencies = [
     "urllib3[socks]>=2.5.0,<3.0",
     "trio>=0.31.0,<1.0",
@@ -32,7 +32,7 @@ dependencies = [
     "certifi>=2025.10.5",
     "typing_extensions>=4.15.0,<5.0",
     "websocket-client>=1.8.0,<2.0",
-    ]
+]
 
 [project.urls]
 homepage = "https://www.selenium.dev"
diff --git a/py/test/selenium/webdriver/firefox/conftest.py b/py/test/selenium/webdriver/firefox/conftest.py
deleted file mode 100644
index 8590135a0bc62..0000000000000
--- a/py/test/selenium/webdriver/firefox/conftest.py
+++ /dev/null
@@ -1,27 +0,0 @@
-# Licensed to the Software Freedom Conservancy (SFC) under one
-# or more contributor license agreements.  See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership.  The SFC licenses this file
-# to you 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 pytest
-
-from selenium.webdriver import Firefox
-
-
-@pytest.fixture
-def driver():
-    driver = Firefox()
-    yield driver
-    driver.quit()
diff --git a/py/test/selenium/webdriver/firefox/ff_installs_addons_tests.py b/py/test/selenium/webdriver/firefox/ff_installs_addons_tests.py
index c7cb6797cd066..42cafa858cf6e 100644
--- a/py/test/selenium/webdriver/firefox/ff_installs_addons_tests.py
+++ b/py/test/selenium/webdriver/firefox/ff_installs_addons_tests.py
@@ -18,12 +18,21 @@
 import os
 import zipfile
 
+import pytest
+
 from selenium.webdriver.common.by import By
 from selenium.webdriver.support.wait import WebDriverWait
 
-extensions = os.path.abspath("../../../../../../test/extensions/")
+for extensions_dir in (
+    os.path.abspath("../../../../../../test/extensions/"),
+    os.path.abspath("../common/extensions/"),
+):
+    extensions = extensions_dir
+    if os.path.exists(extensions_dir):
+        break
 
 
+@pytest.mark.no_driver_after_test
 def test_install_uninstall_signed_addon_xpi(driver, pages):
     extension = os.path.join(extensions, "webextensions-selenium-example.xpi")
 
@@ -41,6 +50,7 @@ def test_install_uninstall_signed_addon_xpi(driver, pages):
     assert len(driver.find_elements(By.ID, "webextensions-selenium-example")) == 0
 
 
+@pytest.mark.no_driver_after_test
 def test_install_uninstall_signed_addon_zip(driver, pages):
     extension = os.path.join(extensions, "webextensions-selenium-example.zip")
 
@@ -58,6 +68,7 @@ def test_install_uninstall_signed_addon_zip(driver, pages):
     assert len(driver.find_elements(By.ID, "webextensions-selenium-example")) == 0
 
 
+@pytest.mark.no_driver_after_test
 def test_install_uninstall_unsigned_addon_zip(driver, pages):
     extension = os.path.join(extensions, "webextensions-selenium-example-unsigned.zip")
 
@@ -75,6 +86,7 @@ def test_install_uninstall_unsigned_addon_zip(driver, pages):
     assert len(driver.find_elements(By.ID, "webextensions-selenium-example")) == 0
 
 
+@pytest.mark.no_driver_after_test
 def test_install_uninstall_signed_addon_dir(driver, pages):
     zip = os.path.join(extensions, "webextensions-selenium-example.zip")
 
@@ -96,6 +108,7 @@ def test_install_uninstall_signed_addon_dir(driver, pages):
     assert len(driver.find_elements(By.ID, "webextensions-selenium-example")) == 0
 
 
+@pytest.mark.no_driver_after_test
 def test_install_uninstall_unsigned_addon_dir(driver, pages):
     zip = os.path.join(extensions, "webextensions-selenium-example-unsigned.zip")
     target = os.path.join(extensions, "webextensions-selenium-example-unsigned-unzip")