diff --git a/Python3.md b/Python3.md
index 79e354c..ba690f6 100644
--- a/Python3.md
+++ b/Python3.md
@@ -27,7 +27,7 @@ Then:
 4. Now run T's tests on Python 3.
 5. Fix any problems caught by the tests.
 6. Add both M and T to `allmydata/util/_python3.py`.
-7. TODO: Not yet possible, but once the ratchet infrastructure is in place, update the should-be-passing-on-Python-3 tests list to include the tests in T plus any other newly passing tests, so that future development doesn't regress Python 3 support.
+7. Run `tox -e py36` (or equivalent) to update the should-be-passing-on-Python-3 tests list at `misc/python3/passing` to include the tests in T plus any other newly passing tests, so that future development doesn't regress Python 3 support.
 8. Submit for code review.
 9. Check coverage report. If there are uncovered lines, see if you can add tests, or at least file a separate ticket for adding coverage.