How can I detect if anything in my checkbox is selected?

If any of the checkboxes are checked, I want to enable the button. Otherwise, if none are checked, I want to disable the button.

jQuery

        $(document).ready(function() {
  $('.check_list').change(function() {
    if ($(".check_list input:checkbox:checked").length > 0){
      $(".btn").attr('disabled','disabled');
    } else {
      $(".btn").removeAttr('disabled');
    }
  });
});

<script src="http://ift.tt/1oMJErh"></script>
<input type="checkbox" class="check_list" name="check_list[]" value="value1">
<input type="checkbox" class="check_list" name="check_list[]" value="value2">
<input type="checkbox" class="check_list" name="check_list[]" value="value3">
<input type="checkbox" class="check_list" name="check_list[]" value="value4">

<button class="btn" disabled> Button</button>

It works when I check the button. But when I uncheck everything it is still enabled. But it should be disabled