diff --git a/doc/api/resources/orders.rst b/doc/api/resources/orders.rst
index 23c54e3596..9c3b5031d1 100644
--- a/doc/api/resources/orders.rst
+++ b/doc/api/resources/orders.rst
@@ -201,6 +201,7 @@ addon_to                              integer                    Internal ID of
 subevent                              integer                    ID of the date inside an event series this position belongs to (or ``null``).
 pseudonymization_id                   string                     A random ID, e.g. for use in lead scanning apps
 checkins                              list of objects            List of check-ins with this ticket
+├ id                                  integer                    Internal ID of the check-in event
 ├ list                                integer                    Internal ID of the check-in list
 ├ datetime                            datetime                   Time of check-in
 ├ type                                string                     Type of scan (defaults to ``entry``)
diff --git a/src/pretix/api/serializers/order.py b/src/pretix/api/serializers/order.py
index 721125f071..c3687998ca 100644
--- a/src/pretix/api/serializers/order.py
+++ b/src/pretix/api/serializers/order.py
@@ -122,7 +122,7 @@ class AnswerSerializer(I18nAwareModelSerializer):
 class CheckinSerializer(I18nAwareModelSerializer):
     class Meta:
         model = Checkin
-        fields = ('datetime', 'list', 'auto_checked_in', 'type')
+        fields = ('id', 'datetime', 'list', 'auto_checked_in', 'type')
 
 
 class OrderDownloadsField(serializers.Field):
diff --git a/src/tests/api/test_checkin.py b/src/tests/api/test_checkin.py
index 3662095197..06e0f50a6c 100644
--- a/src/tests/api/test_checkin.py
+++ b/src/tests/api/test_checkin.py
@@ -402,6 +402,7 @@ def test_list_all_items_positions(token_client, organizer, event, clist, clist_a
         c = order.positions.first().checkins.create(list=clist_all)
     p1['checkins'] = [
         {
+            'id': c.pk,
             'list': clist_all.pk,
             'datetime': c.datetime.isoformat().replace('+00:00', 'Z'),
             'auto_checked_in': False,
@@ -441,6 +442,7 @@ def test_list_all_items_positions(token_client, organizer, event, clist, clist_a
         c = order.positions.last().checkins.create(list=clist_all)
     p2['checkins'] = [
         {
+            'id': c.pk,
             'list': clist_all.pk,
             'datetime': c.datetime.isoformat().replace('+00:00', 'Z'),
             'auto_checked_in': False,
diff --git a/src/tests/api/test_orders.py b/src/tests/api/test_orders.py
index 3f7216bdc2..8cdf3ebdea 100644
--- a/src/tests/api/test_orders.py
+++ b/src/tests/api/test_orders.py
@@ -810,8 +810,14 @@ def test_orderposition_list(token_client, organizer, event, order, item, subeven
 
     with scopes_disabled():
         cl = event.checkin_lists.create(name="Default")
-        op.checkins.create(datetime=datetime.datetime(2017, 12, 26, 10, 0, 0, tzinfo=UTC), list=cl)
-    res['checkins'] = [{'datetime': '2017-12-26T10:00:00Z', 'list': cl.pk, 'auto_checked_in': False, 'type': 'entry'}]
+        c = op.checkins.create(datetime=datetime.datetime(2017, 12, 26, 10, 0, 0, tzinfo=UTC), list=cl)
+    res['checkins'] = [{
+        'id': c.pk,
+        'datetime': '2017-12-26T10:00:00Z',
+        'list': cl.pk,
+        'auto_checked_in': False,
+        'type': 'entry'
+    }]
     resp = token_client.get(
         '/api/v1/organizers/{}/events/{}/orderpositions/?has_checkin=true'.format(organizer.slug, event.slug))
     assert [res] == resp.data['results']