/* This can only ever happen if someone killed us without locking: */
assert (internals->pipes[1] == -1);
-#ifdef HAVE_EVENTFD
+#if defined (HAVE_SYS_EVENTFD_H)
internals->pipes[0] = internals->pipes[1] = eventfd (0, 0);
if (internals->pipes[0] == -1)
#endif