500 error on Firewall page

On Plinth version 0.13.1. It looks like firewalld is not running for some reason, I will investigate that further. But anyway, the Firewall page shows a 500 error, here is the log:

[2017-03-05 12:49:43,145] plinth.actions INFO     Executing command - ['sudo', '-n', '/usr/share/plinth/actions/firewall', 'get-status']
[2017-03-05 12:49:43,463] django.request ERROR    Internal Server Error: /plinth/sys/firewall/
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/core/handlers/exception.py", line 39, in inner
    response = get_response(request)
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/lib/python3/dist-packages/plinth/modules/firewall/views.py", line 30, in index
    if not firewall.get_enabled_status():
  File "/usr/lib/python3/dist-packages/plinth/modules/firewall/__init__.py", line 68, in get_enabled_status
    return output.split()[0] == 'running'
IndexError: list index out of range