Replacing malloc et al in programs.

Hi,

I just ended up in debugging a program (on NetBSD 10.1/i386) that error 
out in strange ways.

A simple way to get something predictable is to link it static (to avoid 
different placement of dynamic libs) and to link with Electric Fence (to 
get a quick-catch of malloc bugs).

But; it fails to link anymore.  Command line:
% gcc -static -O -L/usr/pkg/lib main.o run.o locate.o -o ragge -lefence
ld: /usr/lib/libc.a(jemalloc.o): in function `malloc':
jemalloc.c:(.text+0x3a4c): multiple definition of `malloc'; 
/usr/pkg/lib/libefence.a(efence.o):/pbulk/work/devel/electric-fence/work/electric-fence-2.1.13/efence.c:825: 
first defined here
ld: /usr/lib/libc.a(jemalloc.o): in function `calloc':
jemalloc.c:(.text+0x4a88): multiple definition of `calloc'; 
/usr/pkg/lib/libefence.a(efence.o):/pbulk/work/devel/electric-fence/work/electric-fence-2.1.13/efence.c:842: 
first defined here
....

This suggests that either jemalloc has been too deeply integrated into 
libc (so that it cannot even be changed) or that there is some bug in ld?
How is replacement of the malloc routines supposed to be done these days?

-- R