We consider the development of anisotropic flow in an expanding system of particles undergoing very few rescatterings, using a kinetic-theoretical description with a nonlinear collision term. We derive the scaling behaviors of the harmonic coefficients $$v_n$$ $v_n$ with the initial-state eccentricities and the mean number of rescatterings, and argue that hexagonal flow $$v_6$$ $v_6$ should follow a nontrivial behavior, different from that of the lower harmonics. Our findings should be observable in experimental data for small systems.