diff --git a/src/pretix/api/serializers/order.py b/src/pretix/api/serializers/order.py
index dca6fba3c..524135369 100644
--- a/src/pretix/api/serializers/order.py
+++ b/src/pretix/api/serializers/order.py
@@ -1315,7 +1315,7 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
             if 'valid_from' not in pos_data and 'valid_until' not in pos_data:
                 valid_from, valid_until = pos_data['item'].compute_validity(
                     requested_start=(
-                        max(requested_valid_from, now())
+                        requested_valid_from
                         if requested_valid_from and pos_data['item'].validity_dynamic_start_choice
                         else now()
                     ),
diff --git a/src/tests/api/test_order_create.py b/src/tests/api/test_order_create.py
index 6b752f72d..3a9c9d0b0 100644
--- a/src/tests/api/test_order_create.py
+++ b/src/tests/api/test_order_create.py
@@ -2459,6 +2459,31 @@ def test_order_create_auto_validity_with_requested_start_limitation(token_client
     assert p.valid_until == p.valid_from + datetime.timedelta(minutes=30)
 
 
+@pytest.mark.django_db
+def test_order_create_auto_validity_with_requested_start_in_past(token_client, organizer, event, item, quota, question):
+    item.validity_mode = 'dynamic'
+    item.validity_dynamic_duration_minutes = 30
+    item.validity_dynamic_start_choice = True
+    item.validity_dynamic_start_choice_day_limit = 24
+    item.save()
+    res = copy.deepcopy(ORDER_CREATE_PAYLOAD)
+    res['positions'][0]['item'] = item.pk
+    res['positions'][0]['answers'][0]['question'] = question.pk
+    res['positions'][0]['requested_valid_from'] = (now() - datetime.timedelta(days=30)).isoformat()
+    del res['positions'][0]['price']
+    resp = token_client.post(
+        '/api/v1/organizers/{}/events/{}/orders/'.format(
+            organizer.slug, event.slug
+        ), format='json', data=res
+    )
+    assert resp.status_code == 201
+    with scopes_disabled():
+        o = Order.objects.get(code=resp.data['code'])
+        p = o.positions.first()
+    assert now() - datetime.timedelta(days=31) < p.valid_from <= now() - datetime.timedelta(days=29)
+    assert p.valid_until == p.valid_from + datetime.timedelta(minutes=30)
+
+
 @pytest.mark.django_db
 def test_order_create_auto_pricing(token_client, organizer, event, item, quota, question):
     res = copy.deepcopy(ORDER_CREATE_PAYLOAD)