If you call check_icmp:
./check_icmp -H some_hostname.domain.org
the output of the performance data rtmin is always 0.0ms, this is not possible.
Example output:
OK - some_hostname.domain.org rta 196.981ms lost 0%|rta=196.981ms;200.000;500.000;0; rtmax=197.168ms;;;; rtmin=0.000ms;;;; pl=0%;40;80;0;100
As you see, rtmin is always 0