The real Ginzburg–Landau equation possesses a family of spatially periodic equilibria. If the wave number of an equilibrium is strictly below the so-called Eckhaus boundary the equilibrium is known to be stable. If the wave number is above the Eckhaus boundary the equilibrium is unstable. Exactly at the Eckhaus boundary spectral stability holds and the aim of this talk is to show that nonlinear stability still occurs. The limit profile is determined by a nonlinear equation since a nonlinear term turns out to be marginal w.r.t. the linearized dynamics. This is joint work with G. Schneider, P. Wittwer, and D. Zimmermann.