diff --git a/src/pretix/base/forms.py b/src/pretix/base/forms.py
index b5e29a3e9e..c1bc2c93e7 100644
--- a/src/pretix/base/forms.py
+++ b/src/pretix/base/forms.py
@@ -40,5 +40,7 @@ class SettingsForm(forms.Form):
     def save(self):
         for name, field in self.fields.items():
             value = self.cleaned_data[name]
-            if self.obj.settings.get(value, as_type=type(value)) != value:
+            if value is None:
+                del self.obj.settings[name]
+            elif self.obj.settings.get(value, as_type=type(value)) != value:
                 self.obj.settings.set(name, value)
diff --git a/src/pretix/base/settings.py b/src/pretix/base/settings.py
index 5a92a8838c..32960dd3b7 100644
--- a/src/pretix/base/settings.py
+++ b/src/pretix/base/settings.py
@@ -1,4 +1,8 @@
 import json
+import decimal
+
+from django.db.models import Model
+from versions.models import Versionable
 
 
 DEFAULTS = {
@@ -33,6 +37,8 @@ class SettingsProxy:
     def _unserialize(self, value, as_type):
         if isinstance(value, as_type):
             return value
+        elif value is None:
+            return None
         elif as_type == int:
             return int(value)
         elif as_type == float:
@@ -41,15 +47,27 @@ class SettingsProxy:
             return json.loads(value)
         elif as_type == bool:
             return value == 'True'
+        elif as_type == decimal.Decimal:
+            return decimal.Decimal(value)
+        elif issubclass(as_type, Versionable):
+            return as_type.objects.current.get(identity=value)
+        elif issubclass(as_type, Model):
+            return as_type.objects.get(pk=value)
         return value
 
     def _serialize(self, value):
         if isinstance(value, str):
             return value
-        elif isinstance(value, int) or isinstance(value, float) or isinstance(value, bool):
+        elif isinstance(value, int) or isinstance(value, float) \
+                or isinstance(value, bool) or isinstance(value, decimal.Decimal):
             return str(value)
         elif isinstance(value, list) or isinstance(value, bool):
             return json.dumps(value)
+        elif isinstance(value, Versionable):
+            return value.identity
+        elif isinstance(value, Model):
+            return value.pk
+
         raise TypeError('Unable to serialize %s into a setting.' % str(type(value)))
 
     def get(self, key, default=None, as_type=str):
diff --git a/src/pretix/control/views/event.py b/src/pretix/control/views/event.py
index 2dc3e3d101..f07dd8b062 100644
--- a/src/pretix/control/views/event.py
+++ b/src/pretix/control/views/event.py
@@ -131,17 +131,20 @@ class PaymentSettings(EventPermissionRequiredMixin, TemplateView, SingleObjectMi
                 [
                     ('payment_%s__enabled' % provider.identifier,
                      forms.BooleanField(
-                         label=_('Enable payment method')
+                         label=_('Enable payment method'),
+                         required=False
                      )),
                     ('payment_%s__fee_abs' % provider.identifier,
                      forms.DecimalField(
                          label=_('Additional fee'),
-                         help_text=_('Absolute value')
+                         help_text=_('Absolute value'),
+                         required=False
                      )),
                     ('payment_%s__fee_percent' % provider.identifier,
                      forms.DecimalField(
                          label=_('Additional fee'),
-                         help_text=_('Percentage')
+                         help_text=_('Percentage'),
+                         required=False
                      )),
                 ] + [
                     ('payment_%s_%s' % (provider.identifier, k), v)
diff --git a/src/pretix/plugins/banktransfer/payment.py b/src/pretix/plugins/banktransfer/payment.py
index a48e1ddc33..06d13fe044 100644
--- a/src/pretix/plugins/banktransfer/payment.py
+++ b/src/pretix/plugins/banktransfer/payment.py
@@ -12,6 +12,7 @@ class BankTransfer(BasePaymentProvider):
         ('bank_details',
          forms.CharField(
              widget=forms.Textarea,
-             label=_('Bank account details')
+             label=_('Bank account details'),
+             required=False
          ))
     ])