In some finite-element applications, the use of an unfitted mesh can mitigate the complexity of tasks involving mesh generation, although the lack of fit of the mesh and material interface may cause a large numerical error around the interface. This paper presents a new homogenization technique that reduces the error caused by the lack of fit. The proposed technique determines the material properties of the unfitted elements, so as to guarantee that numerical solutions coincide with the analytical solution, in the simplest situation, where the field is uniform in each of the two materials around a flat interface. Numerical tests demonstrate the effectiveness of the new technique.Index Terms-Anisotropy, finite-element (FE) method, moving interface, unfitted mesh.