[Exim] Exim 3.03 bug on IRIX 6.5 system

I've compiled exim 3.03 for use on an IRIX 6.5 system, and
I'm seeing a funny bug:

Received: from [255.255.255.255] (helo=serenity.mcc.ac.uk)
        by afs.mcc.ac.uk with esmtp (Exim 3.03 #2)
        id 11ZFY4-0007IJ-00
        for zlsiial@???; Thu, 07 Oct 1999 16:33:40 +0100

All of the IP addresses are appearing as 255.255.255.255. Has
anyone seen this?

I've had to compile the binary on a different IRIX 6.5 system,
and worry that the difference between the two OSes is causing
the problem (there's no compiler at the moment on the mail server).

     -- Owen
     LeBlanc@???