Как проверить мой docker-compose.yml?

Я создаю стек контейнера, используя docker-compose. Тем не менее, запустив

docker-compose up

Я получаю довольно загадочное сообщение об ошибке:

Traceback (most recent call last):
  File "/usr/local/bin/docker-compose", line 9, in <module>
    load_entry_point('docker-compose==1.4.2', 'console_scripts', 'docker-compose')()
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/main.py", line 39, in main
    command.sys_dispatch()
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/docopt_command.py", line 21, in sys_dispatch
    self.dispatch(sys.argv[1:], None)
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/command.py", line 27, in dispatch
    super(Command, self).dispatch(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/docopt_command.py", line 24, in dispatch
    self.perform_command(*self.parse(argv, global_options))
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/command.py", line 57, in perform_command
    verbose=options.get('--verbose'))
  File "/usr/local/lib/python2.7/dist-packages/compose/cli/command.py", line 78, in get_project
    config.load(config_details),
  File "/usr/local/lib/python2.7/dist-packages/compose/config.py", line 138, in load
    for service_name, service_dict in list(dictionary.items()):
AttributeError: 'NoneType' object has no attribute 'items'

Как отлаживать? Я проверил, что yml действителен, но он не работает.