Inherit size of particles from parent

Problem: I have a particle system attached to a transform which is scale 1. This transform is the child of a parent with scale 0.2. The particles have a size 1. They are rendered as being the same size af the top-level parent, and not the transform it is connected to.

 Root - scale 0.2
 -- Child - scale 1
 ---- Particle system - size 1

How do I make the particles have sizes relative to its transform, and not to the world scale?