Richy, Ralph, Thanks for the patience and support :) When I disable shared-libs the tests work well. And with shared-libs on again Ralphs suggestion gives the following result: [andrej@diggn:~/source/cln_1.1.9/tests]$ ../libtool --mode=execute gdb ./exam GNU gdb 6.3 Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i486-slackware-linux"...Using host libthread_db library "/lib/libthread_db.so.1". Function "cl_abort" not defined. (gdb) run Starting program: /home/andrej/source/cln_1.1.9/tests/.libs/lt-exam Program received signal SIGSEGV, Segmentation fault. 0x40051b6e in cl_inc_pointer_refcount (pointer=0x0) at object.h:205 205 pointer->refcount++; Current language: auto; currently c++ (gdb) Cheers, Tink