When using a custom class to store a ctype value, passing that class as a function argument explicitly declared to be a pointer type fails to pass the _as_parameter_ class attribute as a pointer and instead raises a TypeError.

For example:
>>> from ctypes import *
>>> from ctypes.wintypes import *
>>>
>>> class CustomPHKEY(object):
...     def __init__(self, value):
...             self._as_parameter_ = HKEY(value)
...
>>>
>>> function = windll.function
>>> function.argtypes = [POINTER(HKEY)]
>>> function.restype = LONG
>>> result = CustomPHKEY(0)
>>> function(result)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ctypes.ArgumentError: argument 1: <type 'exceptions.TypeError'>: expected LP_c_void_p instance instead of c_void_p

Shouldn't ctypes apply the required byref() conversion automatically? Or is this behavior normal and automatic byref() only concerns native ctypes types?

I only flagged Python 3.5 and Python 2.7 since they are the only ones I explicitly tested this on but I suspect other versions are affected.