iptables module recent: how to get the --mask parameter working

i am trying to get --mask working in the module xt_recent. the manual states: --mask netmask but does not state howto.
i tried 255.255.255.248, 29 and /29, non of these worked, error: iptables v1.6.2: unknown option "--mask"

according to the history of commit 55cf7be by @Edrikk the mask parameter was implemented on 2012-Jul-31 in iptables-1.4.15.

has anyone succeeded in using the mask parameter?