diff --git a/db/Calendar.py b/db/Calendar.py
index 1b93571..c3bc0da 100644
--- a/db/Calendar.py
+++ b/db/Calendar.py
@@ -29,6 +29,7 @@ class Calendar(Base):
     server = Column(BigInteger, nullable=False)
     calendar = Column(Text)
     calendar_update = Column(DateTime)
+    last_notify = Column(DateTime, nullable=False, default=datetime.now())
 
     calendars_notify = relationship("CalendarNotify", backref="calendar", lazy="subquery")
 
@@ -58,6 +59,7 @@ class Calendar(Base):
         return list(filter(lambda x: x.begin.date() >= first_date and x.end.date() <= last_date, events))
 
     async def notify(self, bot: Bot, event: ics.Event):
+        self.last_notify = datetime.now()
         for n in self.calendars_notify:
             bot.loop.create_task(n.notify(bot, event))
 
diff --git a/extensions/calendar.py b/extensions/calendar.py
index 788b286..7b968e7 100644
--- a/extensions/calendar.py
+++ b/extensions/calendar.py
@@ -242,7 +242,8 @@ class Calendar(commands.Cog):
         now = datetime.now().replace(tzinfo=timezone.utc).astimezone(tz=None)
         for c in s.query(db.Calendar).all():
             for e in c.events(now.date(), now.date()):
-                if xor(e.begin >= now - timedelta(minutes=30), e.begin >= now - timedelta(minutes=10)):
+                if xor(c.last_notify < e.begin - timedelta(minutes=30) <= now,
+                       c.last_notify < e.begin - timedelta(minutes=10) <= now):
                     self.bot.loop.create_task(await c.notify(self.bot, e))
             if s.is_modified(c):
                 s.add(c)