diff --git a/src/FtpConnection.cc b/src/FtpConnection.cc
index 9fc3ac80..30638fa2 100644
--- a/src/FtpConnection.cc
+++ b/src/FtpConnection.cc
@@ -60,10 +60,6 @@
 
 namespace aria2 {
 
-const std::string FtpConnection::A("A");
-
-const std::string FtpConnection::I("I");
-
 FtpConnection::FtpConnection
 (cuid_t cuid,
  const SocketHandle& socket,
@@ -89,7 +85,7 @@ bool FtpConnection::sendUser()
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, "USER ********"));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -103,7 +99,7 @@ bool FtpConnection::sendPass()
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, "PASS ********"));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -112,18 +108,12 @@ bool FtpConnection::sendPass()
 bool FtpConnection::sendType()
 {
   if(socketBuffer_.sendBufferIsEmpty()) {
-    std::string type;
-    if(option_->get(PREF_FTP_TYPE) == V_ASCII) {
-      type = FtpConnection::A;
-    } else {
-      type = FtpConnection::I;
-    }
     std::string request = "TYPE ";
-    request += type;
+    request += (option_->get(PREF_FTP_TYPE) == V_ASCII ? 'A' : 'I');
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_,request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -135,7 +125,7 @@ bool FtpConnection::sendPwd()
     std::string request = "PWD\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_,request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -149,7 +139,7 @@ bool FtpConnection::sendCwd(const std::string& dir)
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_,request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -164,7 +154,7 @@ bool FtpConnection::sendMdtm()
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -179,7 +169,7 @@ bool FtpConnection::sendSize()
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -188,10 +178,10 @@ bool FtpConnection::sendSize()
 bool FtpConnection::sendEpsv()
 {
   if(socketBuffer_.sendBufferIsEmpty()) {
-    static const std::string request("EPSV\r\n");
+    std::string request("EPSV\r\n");
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -200,10 +190,10 @@ bool FtpConnection::sendEpsv()
 bool FtpConnection::sendPasv()
 {
   if(socketBuffer_.sendBufferIsEmpty()) {
-    static const std::string request("PASV\r\n");
+    std::string request("PASV\r\n");
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -237,7 +227,7 @@ bool FtpConnection::sendEprt(const SharedHandle<SocketCore>& serverSocket)
     request += util::uitos(addrinfo.second);
     request += "|\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST, cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -267,7 +257,7 @@ bool FtpConnection::sendPort(const SharedHandle<SocketCore>& serverSocket)
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -285,7 +275,7 @@ bool FtpConnection::sendRest(const SharedHandle<Segment>& segment)
     request += "\r\n";    
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
@@ -300,7 +290,7 @@ bool FtpConnection::sendRetr()
     request += "\r\n";
     A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                     cuid_, request.c_str()));
-    socketBuffer_.pushStr(request);
+    socketBuffer_.pushStrSwap(request);
   }
   socketBuffer_.send();
   return socketBuffer_.sendBufferIsEmpty();
diff --git a/src/HttpConnection.cc b/src/HttpConnection.cc
index ced5090a..3eb55e40 100644
--- a/src/HttpConnection.cc
+++ b/src/HttpConnection.cc
@@ -109,7 +109,7 @@ void HttpConnection::sendRequest(const SharedHandle<HttpRequest>& httpRequest)
   A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                   cuid_,
                   eraseConfidentialInfo(request).c_str()));
-  socketBuffer_.pushStr(request);
+  socketBuffer_.pushStrSwap(request);
   socketBuffer_.send();
   SharedHandle<HttpRequestEntry> entry(new HttpRequestEntry(httpRequest));
   outstandingHttpRequests_.push_back(entry);
@@ -122,7 +122,7 @@ void HttpConnection::sendProxyRequest
   A2_LOG_INFO(fmt(MSG_SENDING_REQUEST,
                   cuid_,
                   eraseConfidentialInfo(request).c_str()));
-  socketBuffer_.pushStr(request);
+  socketBuffer_.pushStrSwap(request);
   socketBuffer_.send();
   SharedHandle<HttpRequestEntry> entry(new HttpRequestEntry(httpRequest));
   outstandingHttpRequests_.push_back(entry);
diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index 318635c6..8b2762fd 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -156,14 +156,14 @@ const std::string& HttpServer::getRequestPath() const
   return lastRequestHeader_->getRequestPath();
 }
 
-void HttpServer::feedResponse(const std::string& text, const std::string& contentType)
+void HttpServer::feedResponse(std::string& text, const std::string& contentType)
 {
   feedResponse("200 OK", "", text, contentType);
 }
 
 void HttpServer::feedResponse(const std::string& status,
                               const std::string& headers,
-                              const std::string& text,
+                              std::string& text,
                               const std::string& contentType)
 {
   std::string httpDate = Time().toHTTPDate();
@@ -194,8 +194,8 @@ void HttpServer::feedResponse(const std::string& status,
 
   header += "\r\n";
   A2_LOG_DEBUG(fmt("HTTP Server sends response:\n%s", header.c_str()));
-  socketBuffer_.pushStr(header);
-  socketBuffer_.pushStr(text);
+  socketBuffer_.pushStrSwap(header);
+  socketBuffer_.pushStrSwap(text);
 }
 
 ssize_t HttpServer::sendResponse()
diff --git a/src/HttpServer.h b/src/HttpServer.h
index c8dbc8c2..665c6d88 100644
--- a/src/HttpServer.h
+++ b/src/HttpServer.h
@@ -84,11 +84,11 @@ public:
 
   const std::string& getRequestPath() const;
 
-  void feedResponse(const std::string& text, const std::string& contentType);
+  void feedResponse(std::string& text, const std::string& contentType);
 
   void feedResponse(const std::string& status,
                     const std::string& headers,
-                    const std::string& text,
+                    std::string& text,
                     const std::string& contentType);
 
   bool authenticate();
diff --git a/src/HttpServerCommand.cc b/src/HttpServerCommand.cc
index 4dd43a7c..9cb0ebe1 100644
--- a/src/HttpServerCommand.cc
+++ b/src/HttpServerCommand.cc
@@ -123,9 +123,10 @@ bool HttpServerCommand::execute()
       }
       if(!httpServer_->authenticate()) {
         httpServer_->disableKeepAlive();
+        std::string text;
         httpServer_->feedResponse("401 Unauthorized",
                                   "WWW-Authenticate: Basic realm=\"aria2\"",
-                                  "","text/html");
+                                  text,"text/html");
         Command* command =
           new HttpServerResponseCommand(getCuid(), httpServer_, e_, socket_);
         e_->addCommand(command);
diff --git a/src/SocketBuffer.cc b/src/SocketBuffer.cc
index 010ba984..a7933fd8 100644
--- a/src/SocketBuffer.cc
+++ b/src/SocketBuffer.cc
@@ -69,6 +69,8 @@ SocketBuffer::StringBufEntry::StringBufEntry(const std::string& s)
   : str_(s)
 {}
 
+SocketBuffer::StringBufEntry::StringBufEntry() {}
+
 ssize_t SocketBuffer::StringBufEntry::send
 (const SharedHandle<SocketCore>& socket, size_t offset)
 {
@@ -80,6 +82,11 @@ bool SocketBuffer::StringBufEntry::final(size_t offset) const
   return str_.size() <= offset;
 }
 
+void SocketBuffer::StringBufEntry::swap(std::string& s)
+{
+  str_.swap(s);
+}
+
 SocketBuffer::SocketBuffer(const SharedHandle<SocketCore>& socket):
   socket_(socket), offset_(0) {}
 
@@ -99,6 +106,15 @@ void SocketBuffer::pushStr(const std::string& data)
   }
 }
 
+void SocketBuffer::pushStrSwap(std::string& data)
+{
+  if(data.size() > 0) {
+    SharedHandle<StringBufEntry> e(new StringBufEntry());
+    e->swap(data);
+    bufq_.push_back(e);
+  }
+}
+
 ssize_t SocketBuffer::send()
 {
   size_t totalslen = 0;
diff --git a/src/SocketBuffer.h b/src/SocketBuffer.h
index f2baeb49..8cdcf3a1 100644
--- a/src/SocketBuffer.h
+++ b/src/SocketBuffer.h
@@ -71,9 +71,11 @@ private:
   class StringBufEntry:public BufEntry {
   public:
     StringBufEntry(const std::string& s);
+    StringBufEntry();
     virtual ssize_t send
     (const SharedHandle<SocketCore>& socket, size_t offset);
     virtual bool final(size_t offset) const;
+    void swap(std::string& s);
   private:
     std::string str_;
   };
@@ -103,6 +105,11 @@ public:
   // Feeds data into queue. This function doesn't send data.
   void pushStr(const std::string& data);
 
+  // Feeds data into queue. This function doesn't send data.  data is
+  // swapped with internal buffer, so after this call, data will be
+  // empty.
+  void pushStrSwap(std::string& data);
+
   // Sends data in queue.  Returns the number of bytes sent.
   ssize_t send();