diff --git a/ryu/controller/controller.py b/ryu/controller/controller.py
index 4aea6bdb..54fb1c95 100644
--- a/ryu/controller/controller.py
+++ b/ryu/controller/controller.py
@@ -233,8 +233,6 @@ class Datapath(ofproto_protocol.ProtocolDesc):
 
         count = 0
         while self.state != DEAD_DISPATCHER:
-            ret = ""
-
             try:
                 ret = self.socket.recv(required_len)
             except SocketTimeout:
diff --git a/ryu/services/protocols/bgp/speaker.py b/ryu/services/protocols/bgp/speaker.py
index fd6af442..31553b27 100644
--- a/ryu/services/protocols/bgp/speaker.py
+++ b/ryu/services/protocols/bgp/speaker.py
@@ -101,7 +101,7 @@ class BgpProtocol(Protocol, Activity):
         Activity.__init__(self, name=activity_name)
         # Intialize instance variables.
         self._peer = None
-        self._recv_buff = ''
+        self._recv_buff = b''
         self._socket = socket
         self._socket.setsockopt(IPPROTO_TCP, TCP_NODELAY, 1)
         self._sendlock = semaphore.Semaphore()