diff --git a/ryu/app/simple_switch_13.py b/ryu/app/simple_switch_13.py
index 06a5d0ed4..907425c9f 100644
--- a/ryu/app/simple_switch_13.py
+++ b/ryu/app/simple_switch_13.py
@@ -85,7 +85,7 @@ def _packet_in_handler(self, ev):
         dst = eth.dst
         src = eth.src
 
-        dpid = datapath.id
+        dpid = format(datapath.id, "d").zfill(16)
         self.mac_to_port.setdefault(dpid, {})
 
         self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port)
diff --git a/ryu/app/simple_switch_rest_13.py b/ryu/app/simple_switch_rest_13.py
index aaf5d5097..31f834f0f 100644
--- a/ryu/app/simple_switch_rest_13.py
+++ b/ryu/app/simple_switch_rest_13.py
@@ -85,21 +85,21 @@ def __init__(self, req, link, data, **config):
     def list_mac_table(self, req, **kwargs):
 
         simple_switch = self.simple_switch_app
-        dpid = dpid_lib.str_to_dpid(kwargs['dpid'])
+        dpid = kwargs['dpid']
 
         if dpid not in simple_switch.mac_to_port:
             return Response(status=404)
 
         mac_table = simple_switch.mac_to_port.get(dpid, {})
         body = json.dumps(mac_table)
-        return Response(content_type='application/json', body=body)
+        return Response(content_type='application/json', text=body)
 
     @route('simpleswitch', url, methods=['PUT'],
            requirements={'dpid': dpid_lib.DPID_PATTERN})
     def put_mac_table(self, req, **kwargs):
 
         simple_switch = self.simple_switch_app
-        dpid = dpid_lib.str_to_dpid(kwargs['dpid'])
+        dpid = kwargs['dpid']
         try:
             new_entry = req.json if req.body else {}
         except ValueError:
@@ -111,6 +111,6 @@ def put_mac_table(self, req, **kwargs):
         try:
             mac_table = simple_switch.set_mac_to_port(dpid, new_entry)
             body = json.dumps(mac_table)
-            return Response(content_type='application/json', body=body)
+            return Response(content_type='application/json', text=body)
         except Exception as e:
             return Response(status=500)