Make Order Notes Required

Im trying to make the ‘Order Notes’ field required. I’m using the code below but it wont work. Help!!

// Hook in
add_filter( ‘woocommerce_checkout_fields’ , ‘custom_override_checkout_fields’ );

// Our hooked in function – $fields is passed via the filter!
function custom_override_checkout_fields( $fields ) {
$fields[‘order_comments’][‘required’] = false;
return $fields;
}