[plt-scheme] syntax/loc for synthesized location data

[I tried sending this to plt-dev but it isn't showing up for some  
reason.]

Is there a reason why the following should fail to attach source  
location information?

 > (define loc
    (datum->syntax #f 'hello (list #f 100 4 4 5)))
 > loc
#<syntax:100:4>
 > (define stx
    (syntax/loc loc
      (list 1 2 3 4 5)))
 > stx
#<syntax:9:6>

Thanks,
Dave