The invention relates to a low-pressure mercury vapor discharge lamp provided with a discharge vessel (10; 210; 310) which encloses a discharge space (11; 211; 311) comprising a filling of mercury and a rare gas in a gastight manner. The discharge vessel (10; 210; 310) further comprises an amalgam (63; 263; 363) which communicates with the discharge space (11; 211; 311). The lamp has discharge means (41a, 41b; 234; 341a, 341b) for maintaining an electric discharge in the discharge vessel (10; 210). The amalgam (63; 263; 363) comprises a bismuth-tin-indium compound having a bismuth (Bi) content in the range between 30