Hairline crack and about to paint

[KiwiKola]

Hairline crack in wall plaster and am about to repaint room as just had ceiling replastered.

Do I need to fix this before painting?

Feels like a much bigger job than just painting or filling in a couple of small holes from nails etc

Yes you should, really.

Proper way of doing it is to rake it out slightly to open up the gap a little. Then fill, using something like Toupret fill flex ideally. You could use caulk or standard poly filler but the Toupret is more suited to that task. Once dry sand back using say 180 grit and paint.

@Lonelycrab damn it but thanks for advice. I have a scraper will that work?

Can do it while waiting for mist coat on ceiling to dry...

Yes scraper is fine. Just to add, the Toupret is not infact sand able (it’s been a while since I used it) so either smooth it off straight after with say a damp cloth, or use something like Gyproc easi fill which you can sand.