Failed to obfuscate BIGINT

[denblackstache]

It fails on a number higher than 148764065110560896 (BigInt / 62)

And then it returns:

PHP Notice:  Uninitialized string offset: -8 in /home/den/test/tiny/vendor/zackkitzmiller/tiny/src/ZackKitzmiller/Tiny.php on line 20
mBJRU5lERf

Any thoughts about BIGINT support? I haven't found a problem yet. Maybe it fails due to the lack of GMP