  We investigate heterotic ground states in four dimensions in which N=4
supersymmetry is spontaneously broken to N=2. N=4 supersymmetry is restored at
a decompactification limit corresponding to $m_{3/2}\to 0$. We calculate the
full moduli dependent threshold corrections and confirm that they are supressed
in the decompactification limit $m_{3/2}\to 0$ as expected from the restoration
of N=4 supersymmetry. This should be contrasted with the behavior of the
standard N=2 groundstates where the coupling blow up linearly with the volume
of the decompactifying manifold. This mechanism provides a solution to the
decompactification problem for the gauge coupling constants.
  We also discuss how the mechanism can be implemented in ground states with
lower supersymmetry.
