Firefox + Selenium. Что я делаю не так?

import os
from selenium import webdriver
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
from selenium.webdriver.firefox.options import Options

options = Options()
options.headless = True

gecko = os.path.normpath(os.path.join(os.path.dirname(__file__), 'firefox', 'geckodriver'))
binary = FirefoxBinary(r'/home/qwentor/firefox/firefox-bin')

driver = webdriver.Firefox(firefox_binary=binary, executable_path=gecko, options=options)

driver.close()

Traceback (most recent call last):
  File "testbrowser2.py", line 14, in <module>
    driver = webdriver.Firefox(firefox_binary=binary, executable_path=gecko, options=options)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/firefox/webdriver.py", line 174, in __init__
    keep_alive=True)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 157, in __init__
    self.start_session(capabilities, browser_profile)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 252, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python3.6/dist-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: invalid argument: can't kill an exited process