TSCH: fix TSCH_CLOCK_TO_SLOTS macro used for deciding whether to leave the TSCH network
/* Convert rtimer ticks to clock and vice versa */
#define TSCH_CLOCK_TO_TICKS(c) (((c) * RTIMER_SECOND) / CLOCK_SECOND)
-#define TSCH_CLOCK_TO_SLOTS(c, timeslot_length) (TSCH_CLOCK_TO_TICKS(c) / timeslot_length)
+#define TSCH_CLOCK_TO_SLOTS(c, timeslot_length) ((TSCH_CLOCK_TO_TICKS(c) + timeslot_length - 1) / timeslot_length)
#endif /* __TSCH_CONST_H__ */
/** @} */
