Index: django/core/serializers/json.py
===================================================================
--- django/core/serializers/json.py	(revision 4752)
+++ django/core/serializers/json.py	(working copy)
@@ -16,7 +16,10 @@
     Convert a queryset to JSON.
     """
     def end_serialization(self):
-        simplejson.dump(self.objects, self.stream, cls=DateTimeAwareJSONEncoder, **self.options)
+        opts = self.options.copy()
+        opts.pop('stream', None)
+        opts.pop('fields', None)
+        simplejson.dump(self.objects, self.stream, cls=DateTimeAwareJSONEncoder, **opts)
         
     def getvalue(self):
         return self.stream.getvalue()