HTML: MaxLength not respected on Safari on Mac?

So I've got this form with a textbox whose MacLength="50". This works on every browser on every OS except if the combination is 'Safari' + 'Mac'!

Meaning it works, for example, on Safari on Windows and it works on Firefox on Mac.

And the weird thing is that even on Safari+Mac it only works in certain cases, like when you add characters to an earlier word in the sentence you've been writing.

Anyone have any idea WHY this happens and how to prevent it?

Thanks!