diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 1a9e4678..9a0d979c 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -48,6 +48,7 @@ HttpsUpstream::HttpsUpstream(ClientHandler *handler)
   : handler_(handler),
     htp_(new http_parser()),
     current_header_length_(0),
+    downstream_(0),
     ioctrl_(handler->get_bev())
 {
   http_parser_init(htp_, HTTP_REQUEST);
@@ -57,10 +58,7 @@ HttpsUpstream::HttpsUpstream(ClientHandler *handler)
 HttpsUpstream::~HttpsUpstream()
 {
   delete htp_;
-  for(std::deque<Downstream*>::iterator i = downstream_queue_.begin();
-      i != downstream_queue_.end(); ++i) {
-    delete *i;
-  }
+  delete downstream_;
 }
 
 void HttpsUpstream::reset_current_header_length()
@@ -78,7 +76,7 @@ int htp_msg_begin(http_parser *htp)
   }
   upstream->reset_current_header_length();
   Downstream *downstream = new Downstream(upstream, 0, 0);
-  upstream->add_downstream(downstream);
+  upstream->attach_downstream(downstream);
   return 0;
 }
 } // namespace
@@ -88,7 +86,7 @@ int htp_uricb(http_parser *htp, const char *data, size_t len)
 {
   HttpsUpstream *upstream;
   upstream = reinterpret_cast<HttpsUpstream*>(htp->data);
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
   downstream->append_request_path(data, len);
   return 0;
 }
@@ -99,7 +97,7 @@ int htp_hdr_keycb(http_parser *htp, const char *data, size_t len)
 {
   HttpsUpstream *upstream;
   upstream = reinterpret_cast<HttpsUpstream*>(htp->data);
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
   if(downstream->get_request_header_key_prev()) {
     downstream->append_last_request_header_key(data, len);
   } else {
@@ -114,7 +112,7 @@ int htp_hdr_valcb(http_parser *htp, const char *data, size_t len)
 {
   HttpsUpstream *upstream;
   upstream = reinterpret_cast<HttpsUpstream*>(htp->data);
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
   if(downstream->get_request_header_key_prev()) {
     downstream->set_last_request_header_value(std::string(data, len));
   } else {
@@ -132,7 +130,7 @@ int htp_hdrs_completecb(http_parser *htp)
   if(ENABLE_LOG) {
     LOG(INFO) << "Upstream https request headers complete " << upstream;
   }
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
 
   downstream->set_request_method(http_method_str((enum http_method)htp->method));
   downstream->set_request_major(htp->http_major);
@@ -175,7 +173,7 @@ int htp_bodycb(http_parser *htp, const char *data, size_t len)
   int rv;
   HttpsUpstream *upstream;
   upstream = reinterpret_cast<HttpsUpstream*>(htp->data);
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
   rv = downstream->push_upload_data_chunk
     (reinterpret_cast<const uint8_t*>(data), len);
   if(rv != 0) {
@@ -194,7 +192,7 @@ int htp_msg_completecb(http_parser *htp)
   }
   HttpsUpstream *upstream;
   upstream = reinterpret_cast<HttpsUpstream*>(htp->data);
-  Downstream *downstream = upstream->get_last_downstream();
+  Downstream *downstream = upstream->get_downstream();
   rv = downstream->end_upload_data();
   if(rv != 0) {
     return -1;
@@ -238,7 +236,7 @@ int HttpsUpstream::on_read()
   evbuffer_drain(input, nread);
   // Well, actually header length + some body bytes
   current_header_length_ += nread;
-  Downstream *downstream = get_top_downstream();
+  Downstream *downstream = get_downstream();
   http_errno htperr = HTTP_PARSER_ERRNO(htp_);
   if(htperr == HPE_PAUSED) {
     if(downstream->get_request_state() == Downstream::CONNECT_FAIL) {
@@ -252,8 +250,7 @@ int HttpsUpstream::on_read()
       if(downstream->get_downstream_connection() == 0) {
         // Error response already be sent
         assert(downstream->get_response_state() == Downstream::MSG_COMPLETE);
-        pop_downstream();
-        delete downstream;
+        delete_downstream();
       } else {
         pause_read(SHRPX_MSG_BLOCK);
       }
@@ -296,7 +293,7 @@ void https_downstream_readcb(bufferevent *bev, void *ptr);
 
 int HttpsUpstream::on_write()
 {
-  Downstream *downstream = get_top_downstream();
+  Downstream *downstream = get_downstream();
   if(downstream) {
     downstream->resume_read(SHRPX_NO_BUFFER);
   }
@@ -357,8 +354,7 @@ void https_downstream_readcb(bufferevent *bev, void *ptr)
           delete handler;
           return;
         } else {
-          upstream->pop_downstream();
-          delete downstream;
+          upstream->delete_downstream();
           // Process next HTTP request
           upstream->resume_read(SHRPX_MSG_BLOCK);
         }
@@ -384,8 +380,7 @@ void https_downstream_readcb(bufferevent *bev, void *ptr)
         return;
       }
       if(downstream->get_request_state() == Downstream::MSG_COMPLETE) {
-        upstream->pop_downstream();
-        delete downstream;
+        upstream->delete_downstream();
         // Process next HTTP request
         upstream->resume_read(SHRPX_MSG_BLOCK);
       }
@@ -452,8 +447,7 @@ void https_downstream_eventcb(bufferevent *bev, short events, void *ptr)
       }
     }
     if(downstream->get_request_state() == Downstream::MSG_COMPLETE) {
-      upstream->pop_downstream();
-      delete downstream;
+      upstream->delete_downstream();
       upstream->resume_read(SHRPX_MSG_BLOCK);
     }
   } else if(events & (BEV_EVENT_ERROR | BEV_EVENT_TIMEOUT)) {
@@ -473,8 +467,7 @@ void https_downstream_eventcb(bufferevent *bev, short events, void *ptr)
       }
     }
     if(downstream->get_request_state() == Downstream::MSG_COMPLETE) {
-      upstream->pop_downstream();
-      delete downstream;
+      upstream->delete_downstream();
       upstream->resume_read(SHRPX_MSG_BLOCK);
     }
   }
@@ -500,7 +493,7 @@ int HttpsUpstream::error_reply(int status_code)
     LOG(FATAL) << "evbuffer_add() failed";
     return -1;
   }
-  Downstream *downstream = get_top_downstream();
+  Downstream *downstream = get_downstream();
   if(downstream) {
     downstream->set_response_state(Downstream::MSG_COMPLETE);
   }
@@ -522,32 +515,21 @@ bufferevent_event_cb HttpsUpstream::get_downstream_eventcb()
   return https_downstream_eventcb;
 }
 
-void HttpsUpstream::add_downstream(Downstream *downstream)
+void HttpsUpstream::attach_downstream(Downstream *downstream)
 {
-  downstream_queue_.push_back(downstream);
+  assert(!downstream_);
+  downstream_ = downstream;
 }
 
-void HttpsUpstream::pop_downstream()
+void HttpsUpstream::delete_downstream()
 {
-  downstream_queue_.pop_front();
+  delete downstream_;
+  downstream_ = 0;
 }
 
-Downstream* HttpsUpstream::get_top_downstream()
+Downstream* HttpsUpstream::get_downstream() const
 {
-  if(downstream_queue_.empty()) {
-    return 0;
-  } else {
-    return downstream_queue_.front();
-  }
-}
-
-Downstream* HttpsUpstream::get_last_downstream()
-{
-  if(downstream_queue_.empty()) {
-    return 0;
-  } else {
-    return downstream_queue_.back();
-  }
+  return downstream_;
 }
 
 int HttpsUpstream::on_downstream_header_complete(Downstream *downstream)
diff --git a/src/shrpx_https_upstream.h b/src/shrpx_https_upstream.h
index 97d59146..5e5c3929 100644
--- a/src/shrpx_https_upstream.h
+++ b/src/shrpx_https_upstream.h
@@ -29,8 +29,6 @@
 
 #include <stdint.h>
 
-#include <deque>
-
 extern "C" {
 #include "http-parser/http_parser.h"
 }
@@ -54,10 +52,9 @@ public:
   virtual bufferevent_data_cb get_downstream_readcb();
   virtual bufferevent_data_cb get_downstream_writecb();
   virtual bufferevent_event_cb get_downstream_eventcb();
-  void add_downstream(Downstream *downstream);
-  void pop_downstream();
-  Downstream* get_top_downstream();
-  Downstream* get_last_downstream();
+  void attach_downstream(Downstream *downstream);
+  void delete_downstream();
+  Downstream* get_downstream() const;
   int error_reply(int status_code);
 
   void pause_read(IOCtrlReason reason);
@@ -73,7 +70,7 @@ private:
   ClientHandler *handler_;
   http_parser *htp_;
   size_t current_header_length_;
-  std::deque<Downstream*> downstream_queue_;
+  Downstream *downstream_;
   IOControl ioctrl_;
 };