Unknown mark warning

When I use the following code to mark a whole test file to be run last:

pytestmark = pytest.mark.last

I always get the following warning at the end of the test run:

=========================== warnings summary ============================
c:\users\rnd10\appdata\local\programs\python\python37-32\lib\site-packages\_pytest\mark\structures.py:332
  c:\users\rnd10\appdata\local\programs\python\python37-32\lib\site-packages\_pytest\mark\structures.py:332: PytestUnknownMarkWarning: Unknown pytest.mark.last - is this a typo?  You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html
    PytestUnknownMarkWarning,

-- Docs: https://docs.pytest.org/en/latest/warnings.html

Note that the ordering works as expected. My version info:

platform win32 -- Python 3.7.3, pytest-5.0.1, py-1.8.0, pluggy-0.12.0
plugins: cov-2.7.1, ordering-0.6, pycharm-0.5.0

[zicvic]

Same here with pytest.mark.first even though it works as intended

[bnavigator]

pytest-ordering des not look like it is still maintained. Use pytest-order instead. Or even better: Make your tests independent of each other, putting common setup and teardown stuff into fixtures!