diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index 1fb46a0f..0e28269d 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -38,7 +38,7 @@
 
 namespace shrpx {
 
-Downstream::Downstream(Upstream *upstream, int stream_id, int priority)
+Downstream::Downstream(Upstream *upstream, int32_t stream_id, int32_t priority)
   : request_bodylen_(0),
     response_bodylen_(0),
     upstream_(upstream),
diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index 90a4b8bb..4fe9b305 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -49,7 +49,7 @@ class DownstreamConnection;
 
 class Downstream {
 public:
-  Downstream(Upstream *upstream, int stream_id, int priority);
+  Downstream(Upstream *upstream, int32_t stream_id, int32_t priority);
   ~Downstream();
   void reset_upstream(Upstream *upstream);
   Upstream* get_upstream() const;
diff --git a/src/shrpx_downstream_queue.cc b/src/shrpx_downstream_queue.cc
index dec8b314..bcfa00b9 100644
--- a/src/shrpx_downstream_queue.cc
+++ b/src/shrpx_downstream_queue.cc
@@ -34,40 +34,53 @@ DownstreamQueue::DownstreamQueue()
 {}
 
 DownstreamQueue::~DownstreamQueue()
+{}
+
+void DownstreamQueue::add_pending(std::unique_ptr<Downstream> downstream)
 {
-  for(auto& kv : pending_downstreams_) {
-    delete kv.second;
+  auto stream_id = downstream->get_stream_id();
+  pending_downstreams_[stream_id] = std::move(downstream);
+}
+
+void DownstreamQueue::add_failure(std::unique_ptr<Downstream> downstream)
+{
+  auto stream_id = downstream->get_stream_id();
+  failure_downstreams_[stream_id] = std::move(downstream);
+}
+
+void DownstreamQueue::add_active(std::unique_ptr<Downstream> downstream)
+{
+  auto stream_id = downstream->get_stream_id();
+  active_downstreams_[stream_id] = std::move(downstream);
+}
+
+std::unique_ptr<Downstream> DownstreamQueue::remove(int32_t stream_id)
+{
+  auto kv = pending_downstreams_.find(stream_id);
+
+  if(kv != std::end(pending_downstreams_)) {
+    auto downstream = std::move((*kv).second);
+    pending_downstreams_.erase(kv);
+    return downstream;
   }
 
-  for(auto& kv : active_downstreams_) {
-    delete kv.second;
+  kv = active_downstreams_.find(stream_id);
+
+  if(kv != std::end(active_downstreams_)) {
+    auto downstream = std::move((*kv).second);
+    active_downstreams_.erase(kv);
+    return downstream;
   }
 
-  for(auto& kv : failure_downstreams_) {
-    delete kv.second;
+  kv = failure_downstreams_.find(stream_id);
+
+  if(kv != std::end(failure_downstreams_)) {
+    auto downstream = std::move((*kv).second);
+    failure_downstreams_.erase(kv);
+    return downstream;
   }
-}
 
-void DownstreamQueue::add_pending(Downstream *downstream)
-{
-  pending_downstreams_[downstream->get_stream_id()] = downstream;
-}
-
-void DownstreamQueue::add_failure(Downstream *downstream)
-{
-  failure_downstreams_[downstream->get_stream_id()] = downstream;
-}
-
-void DownstreamQueue::add_active(Downstream *downstream)
-{
-  active_downstreams_[downstream->get_stream_id()] = downstream;
-}
-
-void DownstreamQueue::remove(Downstream *downstream)
-{
-  pending_downstreams_.erase(downstream->get_stream_id());
-  active_downstreams_.erase(downstream->get_stream_id());
-  failure_downstreams_.erase(downstream->get_stream_id());
+  return nullptr;
 }
 
 Downstream* DownstreamQueue::find(int32_t stream_id)
@@ -75,25 +88,25 @@ Downstream* DownstreamQueue::find(int32_t stream_id)
   auto kv = pending_downstreams_.find(stream_id);
 
   if(kv != std::end(pending_downstreams_)) {
-    return (*kv).second;
+    return (*kv).second.get();
   }
 
   kv = active_downstreams_.find(stream_id);
 
   if(kv != std::end(active_downstreams_)) {
-    return (*kv).second;
+    return (*kv).second.get();
   }
 
   kv = failure_downstreams_.find(stream_id);
 
   if(kv != std::end(failure_downstreams_)) {
-    return (*kv).second;
+    return (*kv).second.get();
   }
 
   return nullptr;
 }
 
-Downstream* DownstreamQueue::pop_pending()
+std::unique_ptr<Downstream> DownstreamQueue::pop_pending()
 {
   auto i = std::begin(pending_downstreams_);
 
@@ -101,7 +114,7 @@ Downstream* DownstreamQueue::pop_pending()
     return nullptr;
   }
 
-  auto downstream = (*i).second;
+  auto downstream = std::move((*i).second);
 
   pending_downstreams_.erase(i);
 
diff --git a/src/shrpx_downstream_queue.h b/src/shrpx_downstream_queue.h
index 04245b54..60cf8b83 100644
--- a/src/shrpx_downstream_queue.h
+++ b/src/shrpx_downstream_queue.h
@@ -30,6 +30,7 @@
 #include <stdint.h>
 
 #include <map>
+#include <memory>
 
 namespace shrpx {
 
@@ -39,12 +40,13 @@ class DownstreamQueue {
 public:
   DownstreamQueue();
   ~DownstreamQueue();
-  void add_pending(Downstream *downstream);
-  void add_failure(Downstream *downstream);
-  void add_active(Downstream *downstream);
+  void add_pending(std::unique_ptr<Downstream> downstream);
+  void add_failure(std::unique_ptr<Downstream> downstream);
+  void add_active(std::unique_ptr<Downstream> downstream);
   // Removes |downstream| from either pending_downstreams_,
-  // active_downstreams_ or failure_downstreams_.
-  void remove(Downstream *downstream);
+  // active_downstreams_ or failure_downstreams_ and returns it
+  // wrapped in std::unique_ptr.
+  std::unique_ptr<Downstream> remove(int32_t stream_id);
   // Finds Downstream object denoted by |stream_id| either in
   // pending_downstreams_, active_downstreams_ or
   // failure_downstreams_.
@@ -55,14 +57,14 @@ public:
   bool pending_empty() const;
   // Pops first Downstream object in pending_downstreams_ and returns
   // it.
-  Downstream* pop_pending();
+  std::unique_ptr<Downstream> pop_pending();
 private:
   // Downstream objects, not processed yet
-  std::map<int32_t, Downstream*> pending_downstreams_;
+  std::map<int32_t, std::unique_ptr<Downstream>> pending_downstreams_;
   // Downstream objects in use, consuming downstream concurrency limit
-  std::map<int32_t, Downstream*> active_downstreams_;
+  std::map<int32_t, std::unique_ptr<Downstream>> active_downstreams_;
   // Downstream objects, failed to connect to downstream server
-  std::map<int32_t, Downstream*> failure_downstreams_;
+  std::map<int32_t, std::unique_ptr<Downstream>> failure_downstreams_;
 };
 
 } // namespace shrpx
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 6b788fd7..22322c6a 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -73,8 +73,7 @@ int on_stream_close_callback
 
   if(downstream->get_request_state() == Downstream::CONNECT_FAIL) {
     upstream->remove_downstream(downstream);
-
-    delete downstream;
+    // downstream was deleted
 
     return 0;
   }
@@ -94,8 +93,7 @@ int on_stream_close_callback
     }
 
     upstream->remove_downstream(downstream);
-
-    delete downstream;
+    // downstream was deleted
 
     return 0;
   }
@@ -105,7 +103,8 @@ int on_stream_close_callback
   // If shrpx_downstream::push_request_headers() failed, the
   // error is handled here.
   upstream->remove_downstream(downstream);
-  delete downstream;
+  // downstream was deleted
+
   // How to test this case? Request sufficient large download
   // and make client send RST_STREAM after it gets first DATA
   // frame chunk.
@@ -117,9 +116,8 @@ int on_stream_close_callback
 int Http2Upstream::upgrade_upstream(HttpsUpstream *http)
 {
   int rv;
-  auto downstream = http->get_downstream();
 
-  auto http2_settings = downstream->get_http2_settings();
+  auto http2_settings = http->get_downstream()->get_http2_settings();
   util::to_base64(http2_settings);
 
   auto settings_payload = base64::decode(std::begin(http2_settings),
@@ -136,16 +134,17 @@ int Http2Upstream::upgrade_upstream(HttpsUpstream *http)
     return -1;
   }
   pre_upstream_.reset(http);
-  http->pop_downstream();
+  auto downstream = http->pop_downstream();
   downstream->reset_upstream(this);
   downstream->set_stream_id(1);
-  downstream_queue_.add_active(downstream);
   downstream->init_upstream_timer();
   downstream->reset_upstream_rtimer();
   downstream->init_response_body_buf();
   downstream->set_stream_id(1);
   downstream->set_priority(0);
 
+  downstream_queue_.add_active(std::move(downstream));
+
   if(LOG_ENABLED(INFO)) {
     ULOG(INFO, this) << "Connection upgraded to HTTP/2";
   }
@@ -272,11 +271,9 @@ int on_begin_headers_callback(nghttp2_session *session,
   }
 
   // TODO Use priority 0 for now
-  auto downstream = new Downstream(upstream,
-                                   frame->hd.stream_id,
-                                   0);
+  auto downstream = util::make_unique<Downstream>
+    (upstream, frame->hd.stream_id, 0);
 
-  upstream->add_pending_downstream(downstream);
   downstream->init_upstream_timer();
   downstream->reset_upstream_rtimer();
   downstream->init_response_body_buf();
@@ -286,6 +283,8 @@ int on_begin_headers_callback(nghttp2_session *session,
   downstream->set_request_major(2);
   downstream->set_request_minor(0);
 
+  upstream->add_pending_downstream(std::move(downstream));
+
   return 0;
 }
 } // namespace
@@ -392,40 +391,41 @@ void Http2Upstream::maintain_downstream_concurrency()
       break;
     }
 
-    initiate_downstream(downstream);
+    initiate_downstream(std::move(downstream));
   }
 }
 
-void Http2Upstream::initiate_downstream(Downstream *downstream)
+void Http2Upstream::initiate_downstream(std::unique_ptr<Downstream> downstream)
 {
   int rv;
 
   auto dconn = handler_->get_downstream_connection();
-  rv = dconn->attach_downstream(downstream);
+  rv = dconn->attach_downstream(downstream.get());
   if(rv != 0) {
-    downstream_queue_.add_failure(downstream);
-
     // downstream connection fails, send error page
-    if(error_reply(downstream, 503) != 0) {
-      rst_stream(downstream, NGHTTP2_INTERNAL_ERROR);
+    if(error_reply(downstream.get(), 503) != 0) {
+      rst_stream(downstream.get(), NGHTTP2_INTERNAL_ERROR);
     }
 
     downstream->set_request_state(Downstream::CONNECT_FAIL);
 
+    downstream_queue_.add_failure(std::move(downstream));
+
     return;
   }
   rv = downstream->push_request_headers();
   if(rv != 0) {
-    downstream_queue_.add_failure(downstream);
 
-    if(error_reply(downstream, 503) != 0) {
-      rst_stream(downstream, NGHTTP2_INTERNAL_ERROR);
+    if(error_reply(downstream.get(), 503) != 0) {
+      rst_stream(downstream.get(), NGHTTP2_INTERNAL_ERROR);
     }
 
+    downstream_queue_.add_failure(std::move(downstream));
+
     return;
   }
 
-  downstream_queue_.add_active(downstream);
+  downstream_queue_.add_active(std::move(downstream));
 
   return;
 }
@@ -837,7 +837,8 @@ void downstream_readcb(bufferevent *bev, void *ptr)
     // because there is no consumer now. Downstream connection is also
     // closed in this case.
     upstream->remove_downstream(downstream);
-    delete downstream;
+    // downstream was deleted
+
     return;
   }
 
@@ -925,7 +926,7 @@ void downstream_eventcb(bufferevent *bev, short events, void *ptr)
       // If stream was closed already, we don't need to send reply at
       // the first place. We can delete downstream.
       upstream->remove_downstream(downstream);
-      delete downstream;
+      // downstream was deleted
 
       return;
     }
@@ -981,7 +982,7 @@ void downstream_eventcb(bufferevent *bev, short events, void *ptr)
 
     if(downstream->get_request_state() == Downstream::STREAM_CLOSED) {
       upstream->remove_downstream(downstream);
-      delete downstream;
+      // downstream was deleted
 
       return;
     }
@@ -1169,14 +1170,15 @@ bufferevent_event_cb Http2Upstream::get_downstream_eventcb()
   return downstream_eventcb;
 }
 
-void Http2Upstream::add_pending_downstream(Downstream *downstream)
+void Http2Upstream::add_pending_downstream
+(std::unique_ptr<Downstream> downstream)
 {
-  downstream_queue_.add_pending(downstream);
+  downstream_queue_.add_pending(std::move(downstream));
 }
 
 void Http2Upstream::remove_downstream(Downstream *downstream)
 {
-  downstream_queue_.remove(downstream);
+  downstream_queue_.remove(downstream->get_stream_id());
 
   maintain_downstream_concurrency();
 }
diff --git a/src/shrpx_http2_upstream.h b/src/shrpx_http2_upstream.h
index f9130e1d..d720e683 100644
--- a/src/shrpx_http2_upstream.h
+++ b/src/shrpx_http2_upstream.h
@@ -54,7 +54,7 @@ public:
   virtual bufferevent_data_cb get_downstream_readcb();
   virtual bufferevent_data_cb get_downstream_writecb();
   virtual bufferevent_event_cb get_downstream_eventcb();
-  void add_pending_downstream(Downstream *downstream);
+  void add_pending_downstream(std::unique_ptr<Downstream> downstream);
   void remove_downstream(Downstream *downstream);
   Downstream* find_downstream(int32_t stream_id);
 
@@ -83,7 +83,7 @@ public:
   void log_response_headers(Downstream *downstream,
                             const std::vector<nghttp2_nv>& nva) const;
   void maintain_downstream_concurrency();
-  void initiate_downstream(Downstream *downstream);
+  void initiate_downstream(std::unique_ptr<Downstream> downstream);
 private:
   DownstreamQueue downstream_queue_;
   std::unique_ptr<HttpsUpstream> pre_upstream_;
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 68651ecb..dc0a2a15 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -50,7 +50,6 @@ const size_t OUTBUF_MAX_THRES = 16*1024;
 HttpsUpstream::HttpsUpstream(ClientHandler *handler)
   : handler_(handler),
     current_header_length_(0),
-    downstream_(nullptr),
     ioctrl_(handler->get_bev())
 {
   http_parser_init(&htp_, HTTP_REQUEST);
@@ -58,9 +57,7 @@ HttpsUpstream::HttpsUpstream(ClientHandler *handler)
 }
 
 HttpsUpstream::~HttpsUpstream()
-{
-  delete downstream_;
-}
+{}
 
 void HttpsUpstream::reset_current_header_length()
 {
@@ -76,8 +73,7 @@ int htp_msg_begin(http_parser *htp)
   }
   upstream->reset_current_header_length();
   // TODO specify 0 as priority for now
-  auto downstream = new Downstream(upstream, 0, 0);
-  upstream->attach_downstream(downstream);
+  upstream->attach_downstream(util::make_unique<Downstream>(upstream, 0, 0));
   return 0;
 }
 } // namespace
@@ -723,28 +719,25 @@ bufferevent_event_cb HttpsUpstream::get_downstream_eventcb()
   return https_downstream_eventcb;
 }
 
-void HttpsUpstream::attach_downstream(Downstream *downstream)
+void HttpsUpstream::attach_downstream(std::unique_ptr<Downstream> downstream)
 {
   assert(!downstream_);
-  downstream_ = downstream;
+  downstream_ = std::move(downstream);
 }
 
 void HttpsUpstream::delete_downstream()
 {
-  delete downstream_;
-  downstream_ = 0;
+  downstream_.reset();
 }
 
 Downstream* HttpsUpstream::get_downstream() const
 {
-  return downstream_;
+  return downstream_.get();
 }
 
-Downstream* HttpsUpstream::pop_downstream()
+std::unique_ptr<Downstream> HttpsUpstream::pop_downstream()
 {
-  auto downstream = downstream_;
-  downstream_ = nullptr;
-  return downstream;
+  return std::unique_ptr<Downstream>(downstream_.release());
 }
 
 int HttpsUpstream::on_downstream_header_complete(Downstream *downstream)
diff --git a/src/shrpx_https_upstream.h b/src/shrpx_https_upstream.h
index 53013831..b2bb3309 100644
--- a/src/shrpx_https_upstream.h
+++ b/src/shrpx_https_upstream.h
@@ -29,6 +29,8 @@
 
 #include <stdint.h>
 
+#include <memory>
+
 #include "http-parser/http_parser.h"
 
 #include "shrpx_upstream.h"
@@ -50,10 +52,10 @@ public:
   virtual bufferevent_data_cb get_downstream_readcb();
   virtual bufferevent_data_cb get_downstream_writecb();
   virtual bufferevent_event_cb get_downstream_eventcb();
-  void attach_downstream(Downstream *downstream);
+  void attach_downstream(std::unique_ptr<Downstream> downstream);
   void delete_downstream();
   Downstream* get_downstream() const;
-  Downstream* pop_downstream();
+  std::unique_ptr<Downstream> pop_downstream();
   int error_reply(unsigned int status_code);
 
   virtual void pause_read(IOCtrlReason reason);
@@ -70,7 +72,7 @@ private:
   ClientHandler *handler_;
   http_parser htp_;
   size_t current_header_length_;
-  Downstream *downstream_;
+  std::unique_ptr<Downstream> downstream_;
   IOControl ioctrl_;
 };
 
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index f5e35ef3..2f7cad7d 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -109,7 +109,8 @@ void on_stream_close_callback
 
   if(downstream->get_request_state() == Downstream::CONNECT_FAIL) {
     upstream->remove_downstream(downstream);
-    delete downstream;
+    // downstrea was deleted
+
     return;
   }
 
@@ -125,7 +126,8 @@ void on_stream_close_callback
       }
     }
     upstream->remove_downstream(downstream);
-    delete downstream;
+    // downstrea was deleted
+
     return;
   }
 
@@ -134,7 +136,8 @@ void on_stream_close_callback
   // If shrpx_downstream::push_request_headers() failed, the
   // error is handled here.
   upstream->remove_downstream(downstream);
-  delete downstream;
+  // downstrea was deleted
+
   // How to test this case? Request sufficient large download
   // and make client send RST_STREAM after it gets first DATA
   // frame chunk.
@@ -153,10 +156,10 @@ void on_ctrl_recv_callback
       ULOG(INFO, upstream) << "Received upstream SYN_STREAM stream_id="
                            << frame->syn_stream.stream_id;
     }
-    auto downstream = new Downstream(upstream,
-                                     frame->syn_stream.stream_id,
-                                     frame->syn_stream.pri);
-    upstream->add_downstream(downstream);
+
+    auto downstream = upstream->add_pending_downstream
+      (frame->syn_stream.stream_id, frame->syn_stream.pri);
+
     downstream->init_upstream_timer();
     downstream->reset_upstream_rtimer();
     downstream->init_response_body_buf();
@@ -256,31 +259,33 @@ void SpdyUpstream::maintain_downstream_concurrency()
       break;
     }
 
-    initiate_downstream(downstream);
+    initiate_downstream(std::move(downstream));
   }
 }
 
-void SpdyUpstream::initiate_downstream(Downstream *downstream)
+void SpdyUpstream::initiate_downstream(std::unique_ptr<Downstream> downstream)
 {
   auto dconn = handler_->get_downstream_connection();
-  int rv = dconn->attach_downstream(downstream);
+  int rv = dconn->attach_downstream(downstream.get());
   if(rv != 0) {
-    downstream_queue_.add_failure(downstream);
-
     // If downstream connection fails, issue RST_STREAM.
-    rst_stream(downstream, SPDYLAY_INTERNAL_ERROR);
+    rst_stream(downstream.get(), SPDYLAY_INTERNAL_ERROR);
     downstream->set_request_state(Downstream::CONNECT_FAIL);
+
+    downstream_queue_.add_failure(std::move(downstream));
+
     return;
   }
   rv = downstream->push_request_headers();
   if(rv != 0) {
-    downstream_queue_.add_failure(downstream);
+    rst_stream(downstream.get(), SPDYLAY_INTERNAL_ERROR);
+
+    downstream_queue_.add_failure(std::move(downstream));
 
-    rst_stream(downstream, SPDYLAY_INTERNAL_ERROR);
     return;
   }
 
-  downstream_queue_.add_active(downstream);
+  downstream_queue_.add_active(std::move(downstream));
 }
 
 namespace {
@@ -566,7 +571,8 @@ void spdy_downstream_readcb(bufferevent *bev, void *ptr)
     // because there is no consumer now. Downstream connection is also
     // closed in this case.
     upstream->remove_downstream(downstream);
-    delete downstream;
+    // downstrea was deleted
+
     return;
   }
 
@@ -654,7 +660,8 @@ void spdy_downstream_eventcb(bufferevent *bev, short events, void *ptr)
       // If stream was closed already, we don't need to send reply at
       // the first place. We can delete downstream.
       upstream->remove_downstream(downstream);
-      delete downstream;
+      // downstrea was deleted
+
       return;
     }
 
@@ -709,7 +716,8 @@ void spdy_downstream_eventcb(bufferevent *bev, short events, void *ptr)
     }
     if(downstream->get_request_state() == Downstream::STREAM_CLOSED) {
       upstream->remove_downstream(downstream);
-      delete downstream;
+      // downstrea was deleted
+
       return;
     }
 
@@ -900,14 +908,20 @@ bufferevent_event_cb SpdyUpstream::get_downstream_eventcb()
   return spdy_downstream_eventcb;
 }
 
-void SpdyUpstream::add_downstream(Downstream *downstream)
+Downstream* SpdyUpstream::add_pending_downstream
+(int32_t stream_id, int32_t priority)
 {
-  downstream_queue_.add_pending(downstream);
+  auto downstream = util::make_unique<Downstream>(this, stream_id, priority);
+  auto res = downstream.get();
+
+  downstream_queue_.add_pending(std::move(downstream));
+
+  return res;
 }
 
 void SpdyUpstream::remove_downstream(Downstream *downstream)
 {
-  downstream_queue_.remove(downstream);
+  downstream_queue_.remove(downstream->get_stream_id());
 
   maintain_downstream_concurrency();
 }
diff --git a/src/shrpx_spdy_upstream.h b/src/shrpx_spdy_upstream.h
index f42a9839..04d23297 100644
--- a/src/shrpx_spdy_upstream.h
+++ b/src/shrpx_spdy_upstream.h
@@ -27,6 +27,8 @@
 
 #include "shrpx.h"
 
+#include <memory>
+
 #include <spdylay/spdylay.h>
 
 #include "shrpx_upstream.h"
@@ -52,7 +54,7 @@ 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);
+  Downstream* add_pending_downstream(int32_t stream_id, int32_t priority);
   void remove_downstream(Downstream *downstream);
   Downstream* find_downstream(int32_t stream_id);
 
@@ -75,7 +77,7 @@ public:
   int handle_ign_data_chunk(size_t len);
 
   void maintain_downstream_concurrency();
-  void initiate_downstream(Downstream *downstream);
+  void initiate_downstream(std::unique_ptr<Downstream> downstream);
 
   nghttp2::util::EvbufferBuffer sendbuf;
 private: