list-style-type: disc reported as an error

Dear team at validator-css,

Thank you for your great facility. 

An incorrect error has just started to come up (the same css previously validated ok) on ul {list-style-type:disc}   and     .square {list-style-type:square}

Value Error : list-style-type disc is not a list-style-type value : disc 
 .square Value Error : list-style-type square is not a list-style-type value : square 

Thank you and Kind Regards
Kelvin