Difference between the observed heliocentric line wavelengths, and the corresponding NIST laboratory restframe wavelengths, for lines with S/N > 3. The radial velocities were determined from the UVB spectra, which thus have a zero mean offset. The teal circles show the offsets without MOLECFIT wavelength correction, and the purple crosses with correction. Evidently, the correction does not always work, and might even degrade the results, such as for LMC-SMP-58. Errors are not shown, as they are mostly within the size of the plotting symbols. The dashed vertical lines indicate the UVB, VIS and NIR spectral ranges (left, middle, right, respectively).