Lithium abundance vs. T_eff for stars selected for a temperature higher than 5900 K (without deep convection) and without extreme deficiency −2.8 < [Fe/H] < −2.0. Within these limits, the abundance of lithium is independent of the temperature and the metallicity: A(Li) ≈ 2.2 (lithium plateau). The new high proper motion star (red star symbol) is located almost exactly at the mean value of the plateau.