Thanks David, so when I
gcc -fPIC -c gmpd_wrap.c gcc -shared -Wl,-soname,libgmpd_wrap.so.1 -o libgmpd_wrap.so.1.0.1 gmpd_wrap.o -lgmp ln -s libgmpd_wrap.so.1.0.1 libgmpd_wrap.so /opt/usr/local/bin/gdc main.d gmpd.d gmpd_im.d -I. -L. -lgmpd_wrap I get the /usr/bin/ld: __gmpn_ior_n: TLS definition in /tmp/ccmF49fr.o section .tbss mismatches non-TLS reference in ./libgmpd_wrap.so ./libgmpd_wrap.so: could not read symbols: Bad value collect2: ld returned 1 exit status again, a mismatch. Oliver