Passing integer Numpy ndarray to ctypes function

I'm having an issue passing a Numpy ndarray of integers to a C function via ctypes. Below is a MWE that shows the problem. First the C function, it just takes an array as an argument prints its values.

#include <stdio.h>

void my_fun(int *array, int num)
{
    for(int i=0; i<num; i++){
        printf("array value: %d \n", array[i]);
    }
}

Now the Python/ctypes implementation:

import numpy as np
import ctypes

c_int_p = ctypes.POINTER(ctypes.c_int)

_sample_lib = np.ctypeslib.load_library('_sample','.')
_sample_lib.my_fun.restype= None
_sample_lib.my_fun.argtypes = [c_int_p, ctypes.c_int]

my_array = np.arange(5,dtype=np.int)

_sample_lib.my_fun(my_array.ctypes.data_as(c_int_p), len(my_array))

Running the Python code produces:

array value: 0
array value: 0
array value: 1
array value: 0
array value: 2

Notice the extra 0's in the array. Why are they there and how do I get rid of them?