I'm working on a simple program that allows the user to populate an initially-empty listbox. If the user presses an alpha key, newt segfaults at listbox.c:636 because item == NULL. Change: if (item->text && (toupper(*item->text) == toupper(ev.u.key))) { to: if (item && item->text && (toupper(*item->text) == toupper(ev.u.key))) { ...and it goes away.