diff --git a/src/pretix/base/reldate.py b/src/pretix/base/reldate.py
index b16cb7907b..41e5611f93 100644
--- a/src/pretix/base/reldate.py
+++ b/src/pretix/base/reldate.py
@@ -71,20 +71,18 @@ class RelativeDateWrapper:
         :param reference:
         :return:
         """
-        from .models import SubEvent, Event, Order
+        from .models import Event, Order, SubEvent
 
         if self.data.base_date_name in ORDER_CHOICES_KEYS:
             if not isinstance(reference, Order):
                 raise ValueError('A order-based relative datetime choice must be used with an order object')
             event = reference.event
-            base_date = getattr(order, self.data.base_date_name)
+            base_date = getattr(reference, self.data.base_date_name)
         elif isinstance(reference, SubEvent):
             event = reference.event
-            base_date = (
-                    getattr(reference, self.data.base_date_name)
-                    or getattr(reference.event, self.data.base_date_name)
-                    or reference.date_from
-            )
+            base_date = (getattr(reference, self.data.base_date_name) or
+                         getattr(reference.event, self.data.base_date_name) or
+                         reference.date_from)
         elif isinstance(reference, Event):
             event = reference
             base_date = getattr(reference, self.data.base_date_name) or event.date_from
@@ -188,7 +186,7 @@ class RelativeDateWrapper:
                         minutes=None,
                         is_after=len(parts) > 4 and parts[4] == "after",
                     )
-            if data.base_date_name in [k[0] for k in ORDER_CHOICES] and parts[4] == "before":
+            if data.base_date_name in [k[0] for k in ORDER_CHOICES] and parts[4] != "after":
                 raise ValueError('ORDER_CHOICE: {} cannot be combined with "before"'.format(data.base_date_name))
             if data.base_date_name not in [k[0] for k in EVENT_CHOICES + ORDER_CHOICES]:
                 raise ValueError('{} is not a valid base date'.format(data.base_date_name))
@@ -569,7 +567,6 @@ class RelativeDateField(RelativeDateTimeField):
         elif data.status == 'relative' and data.rel_days_relationto in ORDER_CHOICES_KEYS and data.rel_days_relation == 'before':
             raise ValidationError(_('A relative date in relation to an order can only be after the order has been placed'))
 
-
         return forms.MultiValueField.clean(self, value)
 
 
diff --git a/src/tests/base/test_reldate.py b/src/tests/base/test_reldate.py
index 821e9aa980..3b0cc4f0d4 100644
--- a/src/tests/base/test_reldate.py
+++ b/src/tests/base/test_reldate.py
@@ -25,7 +25,7 @@ from zoneinfo import ZoneInfo
 import pytest
 from django_scopes import scope
 
-from pretix.base.models import Event, Organizer, Order
+from pretix.base.models import Event, Order, Organizer
 from pretix.base.reldate import RelativeDate, RelativeDateWrapper
 
 TOKYO = ZoneInfo('Asia/Tokyo')
@@ -46,7 +46,6 @@ def event():
     return event
 
 
-
 @pytest.mark.django_db
 def test_absolute_date(event):
     d = datetime(2017, 12, 25, 5, 0, 0, tzinfo=TOKYO)
@@ -149,6 +148,7 @@ def test_unserialize():
     rdw = RelativeDateWrapper.from_string('RELDATE/minutes/60/date_from/')
     assert rdw.data == RelativeDate(days=0, time=None, base_date_name='date_from', minutes=60)
 
+
 @pytest.mark.django_db
 def test_relative_to_order(event):
     with scope(organizer=event.organizer):
@@ -166,6 +166,9 @@ def test_relative_to_order(event):
         rdw = RelativeDateWrapper(RelativeDate(days=1, time=None, base_date_name='datetime', minutes=None))
         assert rdw.datetime(order).astimezone(TOKYO) == datetime(2020, 3, 28, 18, 0, 0, tzinfo=TOKYO)
         assert rdw.to_string() == 'RELDATE/1/-/datetime/'
+        # this is expressible as a RelativeDate but the Wrapper should catch it as invalid when parsing
+        with pytest.raises(ValueError):
+            rdw.from_string(rdw.to_string())
 
         rdw = RelativeDateWrapper(RelativeDate(days=1, time=None, base_date_name='datetime', minutes=None, is_after=True))
         assert rdw.datetime(order).astimezone(TOKYO) == datetime(2020, 3, 30, 18, 0, 0, tzinfo=TOKYO)