Validator failing to comprehend CSS Variables, CSS Variables inside of calc()

Greetings,
I don't regularly use the CSS validator however I needed another opinion and found that it failed miserably in regards to CSS variables.
I write very dynamic code so I'll often combine multiple bits as it saves me a lot of time. In this case CSS variables and calc():

..selector {height: calc(var(--option-height) * 1);}
This resulted in the following false error:
Value Error : height Parse Error

John