Profiles of the strong resonance lines in the spectrum of V4332 Sgr. Spectra are rescaled. The vertical lines mark the centre of the K i lines at –69 km s^-1 and the centre of interstellar absorption features of Na i at –7.2 km s^-1. Top: the Na i profiles, clipped for clarity. The top spectrum shows the intensity-inverted profile of the H i 21 cm line (see text). Middle: the observed K i lines and a theoretical Lorentzian profile. The strongest telluric absorption lines are indicated. Bottom: Ca i and Rb i lines, spectra slightly smoothed to reduce the noise.