Ottava overlapping fermata

[Alf Storm]

Hi LilyPond users!

I am new to this group, so let me introduce myself:
I am a Norwegian hobby pianist/keyboardist that writes music from time 
to time. I have only recently started to use LilyPond, but I already 
find it comfortable to use. I have used Latex a lot, so text based input 
is familiar.

While inputting my first piece I stumbled across a problem I haven't 
been able to solve. The problem arises when I combine cross staff 
beaming with ottava and fermata. The following example shows that the 
ottava bracket overlaps the fermata sign (at least on my system).

\version "2.18.2"

upper = \relative {
  \clef treble
  \key c \major
  \time 2/4

  \change Staff = "lower"
    c8[

  \change Staff = "upper"
    d'' \ottava #1 e' f'\fermata]
}

lower = \relative {
  \clef bass

  s2
}

\score {
  \new PianoStaff
  <<
    \new Staff = "upper" \upper
    \new Staff = "lower" \lower
  >>
}

Is there any way to tweak the ottava height? Or is this a bug I should 
report?

Thanks,
Alf Storm