diff --git a/src/DownloadEngine.cc b/src/DownloadEngine.cc
index e9bb3e43..4cf1f9ef 100644
--- a/src/DownloadEngine.cc
+++ b/src/DownloadEngine.cc
@@ -328,7 +328,7 @@ void DownloadEngine::poolSocket
  const std::string& proxyhost,
  uint16_t proxyport,
  const SharedHandle<SocketCore>& sock,
- const std::map<std::string, std::string>& options,
+ const std::string& options,
  time_t timeout)
 {
   SocketPoolEntry e(sock, options, timeout);
@@ -387,7 +387,7 @@ void DownloadEngine::poolSocket
  const std::string& username,
  const SharedHandle<Request>& proxyRequest,
  const SharedHandle<SocketCore>& socket,
- const std::map<std::string, std::string>& options,
+ const std::string& options,
  time_t timeout)
 {
   if(!proxyRequest) {
@@ -441,7 +441,7 @@ DownloadEngine::popPooledSocket
 
 SharedHandle<SocketCore>
 DownloadEngine::popPooledSocket
-(std::map<std::string, std::string>& options,
+(std::string& options,
  const std::string& ipaddr, uint16_t port,
  const std::string& username,
  const std::string& proxyhost, uint16_t proxyport)
@@ -475,7 +475,7 @@ DownloadEngine::popPooledSocket
 
 SharedHandle<SocketCore>
 DownloadEngine::popPooledSocket
-(std::map<std::string, std::string>& options,
+(std::string& options,
  const std::vector<std::string>& ipaddrs, uint16_t port,
  const std::string& username)
 {
@@ -492,16 +492,18 @@ DownloadEngine::popPooledSocket
 
 DownloadEngine::SocketPoolEntry::SocketPoolEntry
 (const SharedHandle<SocketCore>& socket,
- const std::map<std::string, std::string>& options,
- time_t timeout):
-  socket_(socket),
-  options_(options),
-  timeout_(timeout) {}
+ const std::string& options,
+ time_t timeout)
+  : socket_(socket),
+    options_(options),
+    timeout_(timeout)
+{}
 
 DownloadEngine::SocketPoolEntry::SocketPoolEntry
-(const SharedHandle<SocketCore>& socket, time_t timeout):
-  socket_(socket),
-  timeout_(timeout) {}
+(const SharedHandle<SocketCore>& socket, time_t timeout)
+  : socket_(socket),
+    timeout_(timeout)
+{}
 
 DownloadEngine::SocketPoolEntry::~SocketPoolEntry() {}
 
diff --git a/src/DownloadEngine.h b/src/DownloadEngine.h
index 346f6ab4..91d827f8 100644
--- a/src/DownloadEngine.h
+++ b/src/DownloadEngine.h
@@ -84,15 +84,15 @@ private:
   class SocketPoolEntry {
   private:
     SharedHandle<SocketCore> socket_;
-
-    std::map<std::string, std::string> options_;
+    // protocol specific option string
+    std::string options_;
 
     time_t timeout_;
 
     Timer registeredTime_;
   public:
     SocketPoolEntry(const SharedHandle<SocketCore>& socket,
-                    const std::map<std::string, std::string>& option,
+                    const std::string& option,
                     time_t timeout);
 
     SocketPoolEntry(const SharedHandle<SocketCore>& socket,
@@ -107,7 +107,7 @@ private:
       return socket_;
     }
 
-    const std::map<std::string, std::string>& getOptions() const
+    const std::string& getOptions() const
     {
       return options_;
     }
@@ -242,16 +242,16 @@ public:
                   const std::string& username,
                   const std::string& proxyhost, uint16_t proxyport,
                   const SharedHandle<SocketCore>& sock,
-                  const std::map<std::string, std::string>& options,
+                  const std::string& options,
                   time_t timeout = 15);
 
   void poolSocket(const SharedHandle<Request>& request,
                   const std::string& username,
                   const SharedHandle<Request>& proxyRequest,
                   const SharedHandle<SocketCore>& socket,
-                  const std::map<std::string, std::string>& options,
+                  const std::string& options,
                   time_t timeout = 15);
-    
+
   void poolSocket(const std::string& ipaddr, uint16_t port,
                   const std::string& proxyhost, uint16_t proxyport,
                   const SharedHandle<SocketCore>& sock,
@@ -268,7 +268,7 @@ public:
    const std::string& proxyhost, uint16_t proxyport);
 
   SharedHandle<SocketCore> popPooledSocket
-  (std::map<std::string, std::string>& options,
+  (std::string& options,
    const std::string& ipaddr,
    uint16_t port,
    const std::string& username,
@@ -280,7 +280,7 @@ public:
 
   SharedHandle<SocketCore>
   popPooledSocket
-  (std::map<std::string, std::string>& options,
+  (std::string& options,
    const std::vector<std::string>& ipaddrs,
    uint16_t port,
    const std::string& username);
diff --git a/src/FtpFinishDownloadCommand.cc b/src/FtpFinishDownloadCommand.cc
index ecfdd838..1af8fdce 100644
--- a/src/FtpFinishDownloadCommand.cc
+++ b/src/FtpFinishDownloadCommand.cc
@@ -85,11 +85,9 @@ bool FtpFinishDownloadCommand::execute()
       }
       if(status == 226) {
         if(getOption()->getAsBool(PREF_FTP_REUSE_CONNECTION)) {
-          std::map<std::string, std::string> options;
-          options["baseWorkingDir"] = ftpConnection_->getBaseWorkingDir();
           getDownloadEngine()->poolSocket
             (getRequest(), ftpConnection_->getUser(), createProxyRequest(),
-             getSocket(), options);
+             getSocket(), ftpConnection_->getBaseWorkingDir());
         }
       } else {
         A2_LOG_INFO(fmt("CUID#%" PRId64 " - Bad status for transfer complete.",
diff --git a/src/FtpInitiateConnectionCommand.cc b/src/FtpInitiateConnectionCommand.cc
index 0a5951da..2700b85f 100644
--- a/src/FtpInitiateConnectionCommand.cc
+++ b/src/FtpInitiateConnectionCommand.cc
@@ -76,7 +76,7 @@ Command* FtpInitiateConnectionCommand::createNextCommand
 {
   Command* command;
   if(proxyRequest) {
-    std::map<std::string, std::string> options;
+    std::string options;
     SharedHandle<SocketCore> pooledSocket;
     std::string proxyMethod = resolveProxyMethod(getRequest()->getProtocol());
     if(proxyMethod == V_GET) {
@@ -124,12 +124,13 @@ Command* FtpInitiateConnectionCommand::createNextCommand
     } else {
       setConnectedAddrInfo(getRequest(), hostname, pooledSocket);
       if(proxyMethod == V_TUNNEL) {
+        // options contains "baseWorkingDir"
         command =
           new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
                                     getRequestGroup(), getDownloadEngine(),
                                     pooledSocket,
                                     FtpNegotiationCommand::SEQ_SEND_CWD_PREP,
-                                    options["baseWorkingDir"]);
+                                    options);
       } else if(proxyMethod == V_GET) {
         // Use GET for FTP via HTTP proxy.
         getRequest()->setMethod(Request::METHOD_GET);
@@ -150,7 +151,7 @@ Command* FtpInitiateConnectionCommand::createNextCommand
       }
     }
   } else {
-    std::map<std::string, std::string> options;
+    std::string options;
     SharedHandle<SocketCore> pooledSocket =
       getDownloadEngine()->popPooledSocket
       (options, resolvedAddresses,
@@ -169,12 +170,13 @@ Command* FtpInitiateConnectionCommand::createNextCommand
       getRequest()->setConnectedAddrInfo(hostname, addr, port);
       command = c;
     } else {
+      // options contains "baseWorkingDir"
       command =
         new FtpNegotiationCommand(getCuid(), getRequest(), getFileEntry(),
                                   getRequestGroup(), getDownloadEngine(),
                                   pooledSocket,
                                   FtpNegotiationCommand::SEQ_SEND_CWD_PREP,
-                                  options["baseWorkingDir"]);
+                                  options);
       setConnectedAddrInfo(getRequest(), hostname, pooledSocket);
     }
   }
diff --git a/src/FtpNegotiationCommand.cc b/src/FtpNegotiationCommand.cc
index 662a4746..796910bc 100644
--- a/src/FtpNegotiationCommand.cc
+++ b/src/FtpNegotiationCommand.cc
@@ -959,10 +959,10 @@ bool FtpNegotiationCommand::processSequence
 void FtpNegotiationCommand::poolConnection() const
 {
   if(getOption()->getAsBool(PREF_FTP_REUSE_CONNECTION)) {
-    std::map<std::string, std::string> options;
-    options["baseWorkingDir"] = ftp_->getBaseWorkingDir();
+    // Store ftp_->getBaseWorkingDir() as options
     getDownloadEngine()->poolSocket(getRequest(), ftp_->getUser(),
-                                    createProxyRequest(), getSocket(), options);
+                                    createProxyRequest(), getSocket(),
+                                    ftp_->getBaseWorkingDir());
   }
 }