diff --git a/xos/synchronizer/models/convenience/voltservice.py b/xos/synchronizer/models/convenience/voltservice.py
index 032aabd..22f4188 100644
--- a/xos/synchronizer/models/convenience/voltservice.py
+++ b/xos/synchronizer/models/convenience/voltservice.py
@@ -1,4 +1,3 @@
-
 # Copyright 2017-present Open Networking Foundation
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -13,17 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
 from xosapi.orm import ORMWrapper, register_convenience_wrapper
 from xosapi.convenience.service import ORMWrapperService
 
 import logging as log
 
+
 class ORMWrapperVOLTService(ORMWrapperService):
 
     def get_onu_sn_from_openflow(self, dp_id, port_no):
         """Return the ONU serial number from logical_device informations
-        
+
         example usage:
             volt = VOLTService.objects.first()
             sn = volt.get_onu_from_openflow("of:0000000ce2314000", 2)
@@ -32,21 +31,21 @@
         Arguments:
             dp_id {string} -- The openflow id of the OLT device
             port_no {int} -- The openflow port id (UNI Port)
-        
+
         Returns:
             string -- ONU Serial Number
         """
 
-        log.debug("Searching ONUDevice for %s:%s", (dp_id, port_no))
-        print "Searching ONUDevice for %s:%s", (dp_id, port_no)
+        log.debug("Searching ONUDevice for %s:%s" % (dp_id, port_no))
         try:
             olt = self.stub.OLTDevice.objects.get(dp_id=dp_id)
             uni_ports = self.stub.UNIPort.objects.filter(port_no=port_no)
             onu = [o.onu_device for o in uni_ports if o.onu_device.pon_port.olt_device.id == olt.id][0]
             return onu.serial_number
         except IndexError:
-            log.error("Can't find ONU for %s:%s", (dp_id, port_no))
+            log.error("Can't find ONU for %s:%s" % (dp_id, port_no))
         except Exception:
-            log.exception("Error while finding ONUDevice for %s:%s", (dp_id, port_no))
+            log.exception("Error while finding ONUDevice for %s:%s" % (dp_id, port_no))
 
-register_convenience_wrapper("VOLTService", ORMWrapperVOLTService)
\ No newline at end of file
+
+register_convenience_wrapper("VOLTService", ORMWrapperVOLTService)