[Bro] Problems with tcprs plugin

[Vito Logrillo]

Hi all,
i'm trying to compile the tcprs plugin with the latest bro version
(2.4-267): using the make command i have this error

/tcprs/src/TCPRS_Endpoint.cc: In member function
‘analyzer::tcp::SCORE*
analyzer::tcp::TCPRS_Endpoint::scoreRetransmission(analyzer::tcp::SequenceRange*,
analyzer::tcp::Segment*, analyzer::tcp::RETRANSMISSION_REASON_CODE,
HashKey*)’:
/home/aramis/bro/aux/plugins/tcprs/src/TCPRS_Endpoint.cc:1180:47:
error: call of overloaded ‘abs(unsigned int)’ is ambiguous
      confidence_value *= 1.0 / (abs(i - TRIPLE) + 1.0); //ack distancing
                                               ^

what's wrong?
Thanks