-m 20 salt length

Hi! 

Is it possible to increase the max salt length for -m 20 md5($salt.$pass)?
I've got a 53 character long salt and Hashcat fails to crack it. Working great with less character salts
(salt is: ac8e67b1c8a467b55f0c5de2f69d07ab9ed6f64e5487955f8afd3)

Thanks in advance and for the great tool Atom!