A coding error in the s-Coordinate Primitive Equation Model SPEM has led to misleading statements about the behaviour of the Mellor-Yamada level 2 parameterization of vertical mixing.It has been claimed that the scheme removes static instability only very slowly and preserves statically unstable stratifications for an unrealistic long time.This note corrects this statement by demonstrating that the Mellor-Yamada mixing scheme, if implemented correctly, tends to overestimate rather than underestimate vertical mixing in seasonally ice-covered seas.Similar to other mixing schemes with the same behaviour, this leads to spurious open ocean deep convection, an unrealistic homogenization of the water column, and a significant reduction of sea ice volume.