Infrastructure Software

I have a strange problem. In my Makefile I link the libpthread.so explicitly by using the option "-lpthread". But my program crashes during the first call of

pthread_mutex_init(&mem->mutex_sock,NULL);

with

Program received signal SIGSEGV, Segmentation fault.
0xef770294 in mutex_init () from /usr/lib/libthread.so.1

Funny that it doesn't happen in the libpthread but in libthread! The code itself comes from Linux and should be ok because it works very well there.