Cython raw string literal broken example

cythonize.py

from Cython.Compiler import Options
Options.annotate = True
Options.fast_fail = True

from Cython.Build import cythonize

cythonize(["main.pyx"], language='c++')

main.pyx

from mypxd cimport (
    myInt
)

print(myInt)

mypxd.pxd

# This one works.
# cdef extern from ".\\util.h":

# This one doesn't.
cdef extern from r".\util.h":
    const unsigned myInt

util.h

const unsigned myInt = 32768;

Nice catch. That was the problem.
Adding #cython: language_level=3 to the pxd file solved it.
Thanks!