  We present a method for a non-linear asteroseismic inversion suitable for
gravity-mode pulsators and apply it to slowly pulsating B-type (SPB) stars. Our
inversion method is based on the iterative improvement of a parameterised
static stellar structure model, which in turn is based on constraints from the
observed oscillation periods. We present tests to demonstrate that the method
is successful in recovering the properties of artificial targets both inside
and outside the parameter space. We also present a test of our method on the
well-studied SPB star KIC 7760680. We believe that this method is promising for
carrying out detailed analyses of observations of SPB and $\gamma$ Dor stars
and will provide complementary information to evolutionary models.
