diff --git a/jsignature/fields.py b/jsignature/fields.py
index 926fe35..b6b771e 100644
--- a/jsignature/fields.py
+++ b/jsignature/fields.py
@@ -13,7 +13,7 @@ from .forms import (
     JSIGNATURE_EMPTY_VALUES)
 
 
-class JSignatureField(six.with_metaclass(models.SubfieldBase, models.Field)):
+class JSignatureField(models.Field):
     """
     A model field handling a signature captured with jSignature
     """
diff --git a/jsignature/widgets.py b/jsignature/widgets.py
index 0b56187..e48c726 100644
--- a/jsignature/widgets.py
+++ b/jsignature/widgets.py
@@ -59,7 +59,7 @@ class JSignatureWidget(HiddenInput):
             return json.dumps(value)
         raise ValidationError('Invalid format.')
 
-    def render(self, name, value, attrs=None):
+    def render(self, name, value, attrs=None, renderer=None):
         """ Render widget """
         # Build config
         jsign_id = self.build_jsignature_id(name)