The spectral fits for the U II lines at 4090.13 Å and 4050.04 Å are presented for CS 22891-171 in the left and for HD 187861 in the right panels, respectively. Red lines correspond to spectral syntheses with the adopted U II abundances of −1.35 dex for CS 22891-171 and −1.40 dex for HD 187861. The blue, green, magenta, and black curves have the same meaning as in Figure 3.