Fraction of the Lyα luminosity to the total bolometric luminosity, L(Lyα) / L_bol for SFR = const. as a function of metallicity and IMF. Results for different IMFs are shown using the same colour codes as in Fig. 1 (cf. Table 1). Thin lines show results using our “standard” Lyα predictions; thick lines the improved results accounting for departures from case B at very low metallicity. Note the resulting strong increase of our revised L(Lyα) / L_bol values from solar to very low metallicity!