Call to undefined function: imagettfbbox()

I can't get gd ttf support to compile, no matter what I try. It used to work fine with 4.0.3pl1, and I haven't change/updated any libraries on my system since then. I'm compiling with the following: configure --enable-track-vars --with-apxs=/var/lib/apache/bin/apxs --with-my sql --with-gd-lib --enable-gd-native-ttf --with-ttf=/usr/X11R6 --with-imap - -with-pgsql The --enable-gd-native I picked up from reading the configure script - although 'configure --help' says --enable-gd-imgstrttf, this is not the parameter that the script actually checks for. Watching the configure script do its thing, I get the following confirmation: checking whether to enable truetype string function in gd... yes But alas, when all is said and done, doing a 'strings libphp4.so | grep imagettf' reveals nothing, and the function is still broken. Help...