Fernandéz and Pestana in the 90’s proved that the Hausdorff content of a set E in the unit circle is bounded by the content of its preimage under any inner function of the unit disc fixing the origin. We extend this result in to inner functions whose fixed points lie on the boundary of the disc. To this purpose, we introduce a specific measure, which happens to be of some interest by its own. Time permitting, we will also present some applications. The talk is based on a joint work with Artur Nicolau and Odí Soler, from Universitat Autònoma de Barcelona.