“multiple target patterns” Makefile error

I had it on the Makefile

MAPS+=reverse/db.901:550:2001.ip6.arpa 
lastserial:  ${MAPS}
    ./updateser ${MAPS}

It’s because of the : in the file name.
I solved this with

                      -------- notice
                     /    /
                    v    v
MAPS+=reverse/db.901\:550\:2001.ip6.arpa
lastserial:  ${MAPS}
    ./updateser ${MAPS}