Support for Haiku requires the addition of the following line to the Makefile:

LIB.Haiku= -lnetwork -lbsd

<hr /><i>steveb added on 2011-07-22 22:40:48 UTC:</i><br />
As of [c32b23d626] fossil builds on Haiku R1/Alpha 3.
It links -lnetwork and -lbsd as required