We investigate magnetic properties of lightly doped antiferromagnetic Mott insulators in the presence of nonmagnetic impurities. Within the framework of the t-J model we calculate the doping dependence of the antiferromagnetic order parameter using self-consistent diagrammatic techniques. We show that in the presence of nonmagnetic impurities the antiferromagnetic order is more robust against hole doping in comparison with the impurity-free host, implying that magnetic order can reappear upon Zn doping into lightly hole-doped cuprates. We argue that this is primarily due to the loss of coherence and reduced mobility of the hole quasiparticles caused by impurity scattering. These results are consistent with experimental data on Zn-doped La2-x Srx Cu O4.