Accidental placement with simultaneous music

[John Schlomann]

I'm probably missing a simple fix for this. In the following example the
natural sign on the f4 in the first voice is placed to the left of the a4 in
the second voice. I can't seem to find a way to fix this. Or is this
considered acceptable? The other accidentals in the measure are correct.

 

  \version "2.20.0"

  \relative c' {

   \key d \major

    <<

      { f4 g8 g8 a4 g4 } \\

      { \set fontSize = #-3 a4 bes4 c8 bes8 a8 g8 }

    >>

  }

 

Thank you for any advice.

John