I would use this insted:
```php
if (defined('JSON_C_VERSION') && PHP_INT_SIZE > 4) {
    $expected = 9223372036854775807;
} elseif (defined('JSON_C_VERSION') {
    $expected = '9223372036854775807';
} else {
    $expected = '12345678901234567890';
}
Assert::same( $expected, Json::decode('12345678901234567890') );
```
Well, no. Do sth useful.