Factor H binding protein (fHBP) has been proposed for use in immunising against serogroup B meningococcus (‘MenB’). This antigen can be efficiently adsorbed to an aluminum hydroxyphosphate adjuvant by (i) ensuring that adsorption takes place at a pH which is equal to or below the adjuvant's point of zero charge (PZC), and/or (ii) selecting a fHBP and adjuvant with an isoelectric point/PZC within the range of 5.0 to 7, and/or (iii) selecting a fHBP with an isoelectric point above the adjuvant's PZC and using a buffer to bring the pH to within 1.2 pH units of the PZC. The adsorption is particularly useful for compositions which include multiple fHBP variants, and also in situations where an aluminum hydroxide adjuvant should be avoided. Buffered pharmaceutical compositions can include at least two different meningococcal fHBP antigens, both of which are at least 85% adsorbed to aluminum hydroxyphosphate adjuvant.