diff --git a/src/schedule.c b/src/schedule.c
index 08c58a6..8fa9db8 100644
--- a/src/schedule.c
+++ b/src/schedule.c
@@ -35,7 +35,8 @@ static inline int _slot_set_interval(hexagram_schedule *schedule, size_t i) {
     return _set_interval(schedule, _slot_interval_ns(schedule, i));
 }
 
-static void _ev_notify(hexagram_schedule *schedule) {
+static void _ev_notify(union sigval sv) {
+    hexagram_schedule *schedule = sv.sival_ptr;
     time_t last = -1;
 
     while (schedule->current < schedule->count) {