Python hypothesis: Ensure that input lists have same length

I'm using hypothesis to test a function that takes two lists of equal length as input.

import hypothesis.strategies as st
from hypothesis import assume, given


@given(st.lists(ints, min_size=1),
       st.lists(ints, min_size=1),
       )
def test_my_func(x, y):
    assume(len(x) == len(y))

    # Assertions

This gives me the error message:

FailedHealthCheck: It looks like your strategy is filtering out a lot of data. Health check found 50 filtered examples but only 4 good ones.

The assumption that len(x) == len(y) is filtering out too many inputs. So I would like to generate a random positive number and use that as the length of both x and y. Is there a way this can be done?