Undefined Reference with GMP

>make simple program using GMP
>try to compile
>UNDEFINED REFERENCE

I don't know what I'm doing wrong. gmp.h is included in the source, I'm telling GCC to link GMP's library, I've set the include/lib paths... What's going on?

Also, what I'm using to compile:
gcc -I/usr/local/include -L/usr/local/lib -lgmp fib_dik_gmp.c

Go back to /g/.