zlib problem?

[Victor Grey]

Using a fresh copy of rsync 2.5.4 installed from the ports collection on
FreeBSD  4.5 Release:

Works fine unless I try to copy a large file with -avz, then I get:
rsync: connection unexpectedly closed (1377 bytes read so far)
rsync error: error in rsync protocol data stream (code 12) at io.c(151)

Can copy the same file with -av successfully.

Just wondering if this is a known problem that someone is working on.

(I'm not subscribed to the list, so please reply directly.)

TIA
Victor Grey