For a nonzero choice of the ' angle and the chiral quark mass phase ' one expects the CP-symmetry to be violated. If the chiral quark mass phase ' can be converted to a contribution to the total effective ' angle, it will have to be explained why this effective angle is extremely small instead of being of order one; the particular value of the angle that must be very close to zero (in this case) is an example of a fine-tuning problem in physics. If the phase ' is absorbed in the gamma-matrices, one has to explain why ' is small, but it will not be unnatural to set it equal to zero.