diff --git a/schedule/models/calendars.py b/schedule/models/calendars.py
index 81f8a7de..d37097a7 100644
--- a/schedule/models/calendars.py
+++ b/schedule/models/calendars.py
@@ -231,7 +231,7 @@ class CalendarRelation(models.Model):
     class Meta:
         verbose_name = _("calendar relation")
         verbose_name_plural = _("calendar relations")
-        index_together = [("content_type", "object_id")]
+        indexes = [models.Index(fields=["content_type", "object_id"])]
 
     def __str__(self):
         return "{} - {}".format(self.calendar, self.content_object)
diff --git a/schedule/models/events.py b/schedule/models/events.py
index bf6fa5f1..bc9671c5 100644
--- a/schedule/models/events.py
+++ b/schedule/models/events.py
@@ -92,7 +92,7 @@ class Event(models.Model):
     class Meta:
         verbose_name = _("event")
         verbose_name_plural = _("events")
-        index_together = (("start", "end"),)
+        indexes = [models.Index(fields=["start", "end"])]
 
     def __str__(self):
         return gettext("%(title)s: %(start)s - %(end)s") % {
@@ -571,7 +571,7 @@ class EventRelation(models.Model):
     class Meta:
         verbose_name = _("event relation")
         verbose_name_plural = _("event relations")
-        index_together = [("content_type", "object_id")]
+        indexes = [models.Index(fields=["content_type", "object_id"])]
 
     def __str__(self):
         return "{}({})-{}".format(
@@ -594,7 +594,7 @@ class Occurrence(models.Model):
     class Meta:
         verbose_name = _("occurrence")
         verbose_name_plural = _("occurrences")
-        index_together = (("start", "end"),)
+        indexes = [models.Index(fields=["start", "end"])]
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)