Why does array_count_values silently turns strings to int? [duplicate]

Here is an array with only strings:

$array = ["1", "hello", "1", "world", "hello"];

Notice that "1" is a string.

If I use array_count_values on this array, it seems it silently converts strings to ints.

var_dump(array_count_values($array));

Echos:

array(3) { [1]=> int(2) ["hello"]=> int(2) ["world"]=> int(1) }

1 is now an int. I feel it's a weird behavior. Is it normal? Did I missed something? Is there a way to avoid this behavior?