courier is a fixed pitch font?

In the font panel on OS X (using capi:prompt-for-font) Courier is 
listed under the fixed with fonts. But LispWorks thinks it is variable 
pitch:

(:NAME "Courier" :FAMILY "Courier" :SIZE 10.0 :WEIGHT :REGULAR :SLANT 
:ROMAN :PITCH :VARIABLE)

Is this a bug, or is there some other explanation?

Thanks,

John DeSoi, Ph.D.