diff --git a/src/pretix/base/models/items.py b/src/pretix/base/models/items.py
index 82186e28d..90a19935b 100644
--- a/src/pretix/base/models/items.py
+++ b/src/pretix/base/models/items.py
@@ -1915,6 +1915,15 @@ class Question(LoggedModel):
             if event != item.event:
                 raise ValidationError(_('One or more items do not belong to this event.'))
 
+    def clean(self):
+        if self.valid_date_max and self.valid_date_min and self.valid_date_min > self.valid_date_max:
+            raise ValidationError(_("The maximum date must not be before the minimum value."))
+        if self.valid_datetime_max and self.valid_datetime_min and self.valid_datetime_min > self.valid_datetime_max:
+            raise ValidationError(_("The maximum date must not be before the minimum value."))
+        if self.valid_number_max and self.valid_number_min and self.valid_number_min > self.valid_number_max:
+            raise ValidationError(_("The maximum value must not be lower than the minimum value."))
+        super().clean()
+
 
 class QuestionOption(models.Model):
     question = models.ForeignKey('Question', related_name='options', on_delete=models.CASCADE)