Load fails

Greetings...
   I have a couple of custom functions (written in C) which used to
work just fine.  However, I recently relinked them, and now I get a
failure whenever I try to use them:

ERROR:  Load of file /home/postgres/lib/vcic.so failed:
 /home/postgres/lib/vcic.so: undefined symbol: palloc

   I've tried both of the following commands to link:
    gcc -shared -o vcic.so vcic.o
    ld -G -Bdynamic -o vcic.so vcic.o
having compiled with:
    gcc -fPIC -c -o vcic.o vcic.c

   This doesn't make sense to me, because palloc should be part of the
server binary, right?  So why can't the dynamic loader resolve it?
   This is on a Linux 2.0.34 system with glibc-2.1.2 (a recent
upgrade, could this be causing the problem, now that I've relinked?)
and PostgreSQL 6.5.2 compiled (as were my functions, both times) by
gcc 2.7.2.3.
   Thanks in advance for any ideas...

-Brandon :)