How to get Mypy to realize that sorting two ints gives back two ints

Question

My code is as follows:

from typing import Tuple

a: Tuple[int, int] = tuple(sorted([1, 3]))

Mypy tells me:

Incompatible types in assignment (expression has type "Tuple[int, ...]", variable has type "Tuple[int, int]")

What am I doing wrong? Why can't Mypy figure out that the sorted tuple will give back exactly two integers?