diff --git a/uncloud_pay/migrations/0015_auto_20200523_2132.py b/uncloud_pay/migrations/0015_auto_20200523_2132.py
new file mode 100644
index 0000000..90a241d
--- /dev/null
+++ b/uncloud_pay/migrations/0015_auto_20200523_2132.py
@@ -0,0 +1,26 @@
+# Generated by Django 3.0.6 on 2020-05-23 21:32
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('uncloud_pay', '0014_paymentsettings'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='order',
+            name='recurring_period',
+            field=models.CharField(choices=[(31536000, 'Per 365 days'), (2592000, 'Per 30 days'), (604800, 'Per Week'), (86400, 'Per Day'), (3600, 'Per Hour'), (60, 'Per Minute'), (1, 'Per Second'), (0, 'Onetime')], default=2592000, max_length=32),
+        ),
+        migrations.AlterField(
+            model_name='ordertimothee',
+            name='recurring_period',
+            field=models.CharField(choices=[(31536000, 'Per 365 days'), (2592000, 'Per 30 days'), (604800, 'Per Week'), (86400, 'Per Day'), (3600, 'Per Hour'), (60, 'Per Minute'), (1, 'Per Second'), (0, 'Onetime')], default=2592000, max_length=32),
+        ),
+        migrations.DeleteModel(
+            name='PaymentSettings',
+        ),
+    ]
diff --git a/uncloud_pay/migrations/0016_auto_20200523_2138.py b/uncloud_pay/migrations/0016_auto_20200523_2138.py
new file mode 100644
index 0000000..bcfdd3c
--- /dev/null
+++ b/uncloud_pay/migrations/0016_auto_20200523_2138.py
@@ -0,0 +1,23 @@
+# Generated by Django 3.0.6 on 2020-05-23 21:38
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('uncloud_pay', '0015_auto_20200523_2132'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='order',
+            name='recurring_period',
+            field=models.IntegerField(choices=[(31536000, 'Per 365 days'), (2592000, 'Per 30 days'), (604800, 'Per Week'), (86400, 'Per Day'), (3600, 'Per Hour'), (60, 'Per Minute'), (1, 'Per Second'), (0, 'Onetime')], default=2592000),
+        ),
+        migrations.AlterField(
+            model_name='ordertimothee',
+            name='recurring_period',
+            field=models.IntegerField(choices=[(31536000, 'Per 365 days'), (2592000, 'Per 30 days'), (604800, 'Per Week'), (86400, 'Per Day'), (3600, 'Per Hour'), (60, 'Per Minute'), (1, 'Per Second'), (0, 'Onetime')], default=2592000),
+        ),
+    ]
diff --git a/uncloud_pay/models.py b/uncloud_pay/models.py
index 85c280b..8e6f4e1 100644
--- a/uncloud_pay/models.py
+++ b/uncloud_pay/models.py
@@ -315,8 +315,9 @@ class BillNico(models.Model):
         for order in Order.objects.filter(~Q(recurring_period=RecurringPeriod.ONE_TIME),
                                           Q(starting_date__lt=self.starting_date),
                                           owner=owner):
-            pass
 
+            if order.recurring_period > 0: # avoid div/0 - these are one time payments
+                pass
 
 
 
@@ -661,8 +662,7 @@ class Order(models.Model):
                                   editable=False,
                                   blank=True)
 
-    recurring_period = models.CharField(max_length=32,
-                              choices = RecurringPeriod.choices, default = RecurringPeriod.PER_30D)
+    recurring_period = models.IntegerField(choices = RecurringPeriod.choices, default = RecurringPeriod.PER_30D)
 
     one_time_price = models.DecimalField(default=0.0,
             max_digits=AMOUNT_MAX_DIGITS,
@@ -766,9 +766,8 @@ class OrderTimothee(models.Model):
                                   editable=False,
                                   blank=True)
 
-    recurring_period = models.CharField(max_length=32,
-                              choices = RecurringPeriod.choices,
-                                        default = RecurringPeriod.PER_30D)
+    recurring_period = models.IntegerField(choices = RecurringPeriod.choices,
+                                           default = RecurringPeriod.PER_30D)
 
     # Trigger initial bill generation at order creation.
     def save(self, *args, **kwargs):