Rémi Lapeyre <remi.lapeyre@henki.fr> added the comment: Hi Cheryl, thanks for the ping. I wasn't sure my patch was correct but reading typeobject.c:add_operators(), it is actually more straight-forward than I thought. Serhiy Storchaka: This is indeed a duplicate of issue20092. I believe the solution proposed by Nick Coghlan is better than the one of Amitava Bhattacharyya, "adding a call to `nb_index` (if that slot exists) in `_PyLong_FromNbInt`" though. One thing to note regarding the proposed patch: the following stops to work and raises a RecursionError since __index__ == __int__: class MyInt(int): def __index__(self): return int(self) + 1 I changed test_int_subclass_with_index() as `int(self) + 1` is the same thing as `self + 1` for int subclasses. I don't think this sort of code should appear in the wild but if you think it is important not to break compatibility here, I think I could check for number subclasses before overriding __index__. ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue33039> _______________________________________