\magnifyStaff for dynamics?

[Mason Hock]

\version "2.19.63"
\score {
  <<
    \new Staff \with { \magnifyStaff #(magstep -3) }
    \relative c' { c c c c }
    \new Dynamics \with { \override VerticalAxisGroup.staff-affinity = #UP }
    { s\p\< s s s\f}
  >>
}

shrinks the music staff as expected but does not shrink the dynamics staff.

\version "2.19.63"
\score {
  <<
    \new Staff \with { \magnifyStaff #(magstep -3) }
    \relative c' { c c c c }
    \new Dynamics \with { \override VerticalAxisGroup.staff-affinity = #UP \magnifyStaff #(magstep -3) }
    { s\p\< s s s\f}
  >>
}

gives

In procedure ly:context-property in _expression_ (ly:context-property Staff (quote magnifyStaffValue)):

/home/mason/.guix-profile/share/lilypond/2.19.63/scm/music-functions.scm:2513:19: Wrong type argument in position 1 (expecting Context): #f

Exited with return code 1.

Is there a way to magnify the dynamics staff by the same factor as the music staff?

Thanks,

Mason