Error Compiling PHP 5.1.2

I'm getting the following error when I try to compile PHP 5.1.2 on my
Slackware 10.0 machine:

main/.libs/output.o(.text+0xaf1): In function `php_ob_init_named':
/usr/src/php-5.1.2/main/output.c:429: undefined reference to
`php_ob_gzhandler_check'
collect2: ld returned 1 exit status
make: *** [sapi/cgi/php] Error 1

At first I thought that maybe it just wasn't finding zlib, and googling
the error suggested that to be the case. So I installed zlib, but no
change.

It's entirely likely that the target machine may be missing some
requisite libraries, it was a pretty stripped down installation of
Slackware.

I'm sure this is something simple that I'm just not seeing. Any ideas?


-David