# ifndef EV_USE_REALTIME
# define EV_USE_REALTIME 1
# endif
+# else
+# ifndef EV_USE_MONOTONIC
+# define EV_USE_MONOTONIC 0
+# endif
+# ifndef EV_USE_REALTIME
+# define EV_USE_REALTIME 0
+# endif
# endif
-# if HAVE_SELECT && HAVE_SYS_SELECT_H && !defined (EV_USE_SELECT)
-# define EV_USE_SELECT 1
+# ifndef EV_USE_SELECT
+# if HAVE_SELECT && HAVE_SYS_SELECT_H
+# define EV_USE_SELECT 1
+# else
+# define EV_USE_SELECT 0
+# endif
# endif
-# if HAVE_POLL && HAVE_POLL_H && !defined (EV_USE_POLL)
-# define EV_USE_POLL 1
+# ifndef EV_USE_POLL
+# if HAVE_POLL && HAVE_POLL_H
+# define EV_USE_POLL 1
+# else
+# define EV_USE_POLL 0
+# endif
# endif
-
-# if HAVE_EPOLL_CTL && HAVE_SYS_EPOLL_H && !defined (EV_USE_EPOLL)
-# define EV_USE_EPOLL 1
+
+# ifndef EV_USE_EPOLL
+# if HAVE_EPOLL_CTL && HAVE_SYS_EPOLL_H
+# define EV_USE_EPOLL 1
+# else
+# define EV_USE_EPOLL 0
+# endif
# endif
-
-# if HAVE_KQUEUE && HAVE_SYS_EVENT_H && HAVE_SYS_QUEUE_H && !defined (EV_USE_KQUEUE)
-# define EV_USE_KQUEUE 1
+
+# ifndef EV_USE_KQUEUE
+# if HAVE_KQUEUE && HAVE_SYS_EVENT_H && HAVE_SYS_QUEUE_H
+# define EV_USE_KQUEUE 1
+# else
+# define EV_USE_KQUEUE 0
+# endif
# endif
-
-# if HAVE_PORT_H && HAVE_PORT_CREATE && !defined (EV_USE_PORT)
-# define EV_USE_PORT 1
+
+# ifndef EV_USE_PORT
+# if HAVE_PORT_H && HAVE_PORT_CREATE
+# define EV_USE_PORT 1
+# else
+# define EV_USE_PORT 0
+# endif
# endif
#endif