Offset fermata problem

[Menu Jacques]

Hello folks,

I’d like to obtain the following from Poulenc, in which the fermata is in-between a2 and r4:

I tried with:

\version "2.19.28"

\score {
  \relative c'' {
    \key f \major \time 2/2 | % 147

    <<
      {a2 r4}
      {s2 s16 \fermata s8.}
    >>
    e16 -\markup{\dynamic "ff" \italic "librement"}  ^\markup{\bold "solo"} [ f16 g16 f16 ]
  }
}

but then the fermata is right over the r4.

Thanks for the help!

JM