[plt-scheme] passing-on keyword arguments

I've run into this issue a few times, and thought I'd finally post
here.  I'd like to wrap a function that takes keyword arguments, but
pass-on some/all of the keyword arguments from the outer function to
the inner function.  For example,

(define (inner #:x [x 10]) (* x x))

(define (outer #:x [x 10]) (+ (inner #:x x) 5))

This works, but I'm duplicating code.  Specifically, I had to
duplicate the default value for the "x" argument.  Any nice way of
writing outer and letting it defer to inner to get the default value
for x?

Thanks,
Rob