diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index e71893a8..34669cf2 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -120,10 +120,10 @@ Downstream::Downstream(Upstream *upstream, int32_t stream_id, int32_t priority)
       response_minor_(1), upgrade_request_(false), upgraded_(false),
       http2_upgrade_seen_(false), chunked_request_(false),
       request_connection_close_(false), request_header_key_prev_(false),
-      request_http2_expect_body_(false), chunked_response_(false),
-      response_connection_close_(false), response_header_key_prev_(false),
-      response_trailer_key_prev_(false), expect_final_response_(false),
-      request_pending_(false) {
+      request_trailer_key_prev_(false), request_http2_expect_body_(false),
+      chunked_response_(false), response_connection_close_(false),
+      response_header_key_prev_(false), response_trailer_key_prev_(false),
+      expect_final_response_(false), request_pending_(false) {
 
   ev_timer_init(&upstream_rtimer_, &upstream_rtimeoutcb, 0.,
                 get_config()->stream_read_timeout);
@@ -288,6 +288,45 @@ const std::string &Downstream::get_assembled_request_cookie() const {
   return assembled_request_cookie_;
 }
 
+namespace {
+void add_header(bool &key_prev, size_t &sum, Headers &headers, std::string name,
+                std::string value) {
+  key_prev = true;
+  sum += name.size() + value.size();
+  headers.emplace_back(std::move(name), std::move(value));
+}
+} // namespace
+
+namespace {
+void append_last_header_key(bool key_prev, size_t &sum, Headers &headers,
+                            const char *data, size_t len) {
+  assert(key_prev);
+  sum += len;
+  auto &item = headers.back();
+  item.name.append(data, len);
+}
+} // namespace
+
+namespace {
+void append_last_header_value(bool key_prev, size_t &sum, Headers &headers,
+                              const char *data, size_t len) {
+  assert(!key_prev);
+  sum += len;
+  auto &item = headers.back();
+  item.value.append(data, len);
+}
+} // namespace
+
+namespace {
+void set_last_header_value(bool &key_prev, size_t &sum, Headers &headers,
+                           const char *data, size_t len) {
+  key_prev = false;
+  sum += len;
+  auto &item = headers.back();
+  item.value.assign(data, len);
+}
+} // namespace
+
 namespace {
 int index_headers(http2::HeaderIndex &hdidx, Headers &headers,
                   int64_t &content_length) {
@@ -334,16 +373,13 @@ Downstream::get_request_header(const std::string &name) const {
 }
 
 void Downstream::add_request_header(std::string name, std::string value) {
-  request_header_key_prev_ = true;
-  request_headers_sum_ += name.size() + value.size();
-  request_headers_.emplace_back(std::move(name), std::move(value));
+  add_header(request_header_key_prev_, request_headers_sum_, request_headers_,
+             std::move(name), std::move(value));
 }
 
-void Downstream::set_last_request_header_value(std::string value) {
-  request_header_key_prev_ = false;
-  request_headers_sum_ += value.size();
-  Headers::value_type &item = request_headers_.back();
-  item.value = std::move(value);
+void Downstream::set_last_request_header_value(const char *data, size_t len) {
+  set_last_header_value(request_header_key_prev_, request_headers_sum_,
+                        request_headers_, data, len);
 }
 
 void Downstream::add_request_header(const uint8_t *name, size_t namelen,
@@ -360,18 +396,14 @@ bool Downstream::get_request_header_key_prev() const {
 }
 
 void Downstream::append_last_request_header_key(const char *data, size_t len) {
-  assert(request_header_key_prev_);
-  request_headers_sum_ += len;
-  auto &item = request_headers_.back();
-  item.name.append(data, len);
+  append_last_header_key(request_header_key_prev_, request_headers_sum_,
+                         request_headers_, data, len);
 }
 
 void Downstream::append_last_request_header_value(const char *data,
                                                   size_t len) {
-  assert(!request_header_key_prev_);
-  request_headers_sum_ += len;
-  auto &item = request_headers_.back();
-  item.value.append(data, len);
+  append_last_header_value(request_header_key_prev_, request_headers_sum_,
+                           request_headers_, data, len);
 }
 
 void Downstream::clear_request_headers() {
@@ -397,6 +429,31 @@ const Headers &Downstream::get_request_trailers() const {
   return request_trailers_;
 }
 
+void Downstream::add_request_trailer(std::string name, std::string value) {
+  add_header(request_trailer_key_prev_, request_headers_sum_, request_trailers_,
+             std::move(name), std::move(value));
+}
+
+void Downstream::set_last_request_trailer_value(const char *data, size_t len) {
+  set_last_header_value(request_trailer_key_prev_, request_headers_sum_,
+                        request_trailers_, data, len);
+}
+
+bool Downstream::get_request_trailer_key_prev() const {
+  return request_trailer_key_prev_;
+}
+
+void Downstream::append_last_request_trailer_key(const char *data, size_t len) {
+  append_last_header_key(request_trailer_key_prev_, request_headers_sum_,
+                         request_trailers_, data, len);
+}
+
+void Downstream::append_last_request_trailer_value(const char *data,
+                                                   size_t len) {
+  append_last_header_value(request_trailer_key_prev_, request_headers_sum_,
+                           request_trailers_, data, len);
+}
+
 void Downstream::set_request_method(std::string method) {
   request_method_ = std::move(method);
 }
@@ -607,16 +664,13 @@ void Downstream::rewrite_location_response_header(
 }
 
 void Downstream::add_response_header(std::string name, std::string value) {
-  response_header_key_prev_ = true;
-  response_headers_sum_ += name.size() + value.size();
-  response_headers_.emplace_back(std::move(name), std::move(value));
+  add_header(response_header_key_prev_, response_headers_sum_,
+             response_headers_, std::move(name), std::move(value));
 }
 
-void Downstream::set_last_response_header_value(std::string value) {
-  response_header_key_prev_ = false;
-  response_headers_sum_ += value.size();
-  auto &item = response_headers_.back();
-  item.value = std::move(value);
+void Downstream::set_last_response_header_value(const char *data, size_t len) {
+  set_last_header_value(response_header_key_prev_, response_headers_sum_,
+                        response_headers_, data, len);
 }
 
 void Downstream::add_response_header(std::string name, std::string value,
@@ -641,18 +695,14 @@ bool Downstream::get_response_header_key_prev() const {
 }
 
 void Downstream::append_last_response_header_key(const char *data, size_t len) {
-  assert(response_header_key_prev_);
-  response_headers_sum_ += len;
-  auto &item = response_headers_.back();
-  item.name.append(data, len);
+  append_last_header_key(response_header_key_prev_, response_headers_sum_,
+                         response_headers_, data, len);
 }
 
 void Downstream::append_last_response_header_value(const char *data,
                                                    size_t len) {
-  assert(!response_header_key_prev_);
-  response_headers_sum_ += len;
-  auto &item = response_headers_.back();
-  item.value.append(data, len);
+  append_last_header_value(response_header_key_prev_, response_headers_sum_,
+                           response_headers_, data, len);
 }
 
 void Downstream::clear_response_headers() {
@@ -681,9 +731,13 @@ unsigned int Downstream::get_response_http_status() const {
 }
 
 void Downstream::add_response_trailer(std::string name, std::string value) {
-  response_trailer_key_prev_ = true;
-  response_headers_sum_ += name.size() + value.size();
-  response_trailers_.emplace_back(std::move(name), std::move(value));
+  add_header(response_trailer_key_prev_, response_headers_sum_,
+             response_trailers_, std::move(name), std::move(value));
+}
+
+void Downstream::set_last_response_trailer_value(const char *data, size_t len) {
+  set_last_header_value(response_trailer_key_prev_, response_headers_sum_,
+                        response_trailers_, data, len);
 }
 
 bool Downstream::get_response_trailer_key_prev() const {
@@ -692,25 +746,14 @@ bool Downstream::get_response_trailer_key_prev() const {
 
 void Downstream::append_last_response_trailer_key(const char *data,
                                                   size_t len) {
-  assert(response_trailer_key_prev_);
-  response_headers_sum_ += len;
-  auto &item = response_trailers_.back();
-  item.name.append(data, len);
+  append_last_header_key(response_trailer_key_prev_, response_headers_sum_,
+                         response_trailers_, data, len);
 }
 
 void Downstream::append_last_response_trailer_value(const char *data,
                                                     size_t len) {
-  assert(!response_trailer_key_prev_);
-  response_headers_sum_ += len;
-  auto &item = response_trailers_.back();
-  item.value.append(data, len);
-}
-
-void Downstream::set_last_response_trailer_value(std::string value) {
-  response_trailer_key_prev_ = false;
-  response_headers_sum_ += value.size();
-  auto &item = response_trailers_.back();
-  item.value = std::move(value);
+  append_last_header_value(response_trailer_key_prev_, response_headers_sum_,
+                           response_trailers_, data, len);
 }
 
 void Downstream::set_response_http_status(unsigned int status) {
diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index 8ffff731..e1a51f4c 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -113,7 +113,7 @@ public:
   // no such header is found, returns nullptr.
   const Headers::value_type *get_request_header(const std::string &name) const;
   void add_request_header(std::string name, std::string value);
-  void set_last_request_header_value(std::string value);
+  void set_last_request_header_value(const char *data, size_t len);
 
   void add_request_header(const uint8_t *name, size_t namelen,
                           const uint8_t *value, size_t valuelen, bool no_index,
@@ -131,6 +131,11 @@ public:
   void add_request_trailer(const uint8_t *name, size_t namelen,
                            const uint8_t *value, size_t valuelen, bool no_index,
                            int16_t token);
+  void add_request_trailer(std::string name, std::string value);
+  void set_last_request_trailer_value(const char *data, size_t len);
+  bool get_request_trailer_key_prev() const;
+  void append_last_request_trailer_key(const char *data, size_t len);
+  void append_last_request_trailer_value(const char *data, size_t len);
 
   void set_request_method(std::string method);
   const std::string &get_request_method() const;
@@ -206,7 +211,7 @@ public:
   // Rewrites the location response header field.
   void rewrite_location_response_header(const std::string &upstream_scheme);
   void add_response_header(std::string name, std::string value);
-  void set_last_response_header_value(std::string value);
+  void set_last_response_header_value(const char *data, size_t len);
 
   void add_response_header(std::string name, std::string value, int16_t token);
   void add_response_header(const uint8_t *name, size_t namelen,
@@ -226,10 +231,10 @@ public:
                             const uint8_t *value, size_t valuelen,
                             bool no_index, int16_t token);
   void add_response_trailer(std::string name, std::string value);
+  void set_last_response_trailer_value(const char *data, size_t len);
   bool get_response_trailer_key_prev() const;
   void append_last_response_trailer_key(const char *data, size_t len);
   void append_last_response_trailer_value(const char *data, size_t len);
-  void set_last_response_trailer_value(std::string value);
 
   unsigned int get_response_http_status() const;
   void set_response_http_status(unsigned int status);
@@ -405,6 +410,7 @@ private:
   bool chunked_request_;
   bool request_connection_close_;
   bool request_header_key_prev_;
+  bool request_trailer_key_prev_;
   bool request_http2_expect_body_;
 
   bool chunked_response_;
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index 8630815d..be8981cd 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -594,13 +594,13 @@ int htp_hdr_valcb(http_parser *htp, const char *data, size_t len) {
   auto downstream = static_cast<Downstream *>(htp->data);
   if (downstream->get_response_state() == Downstream::INITIAL) {
     if (downstream->get_response_header_key_prev()) {
-      downstream->set_last_response_header_value(std::string(data, len));
+      downstream->set_last_response_header_value(data, len);
     } else {
       downstream->append_last_response_header_value(data, len);
     }
   } else {
     if (downstream->get_response_trailer_key_prev()) {
-      downstream->set_last_response_trailer_value(std::string(data, len));
+      downstream->set_last_response_trailer_value(data, len);
     } else {
       downstream->append_last_response_trailer_value(data, len);
     }
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 1020adb1..b14a8664 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -83,14 +83,19 @@ namespace {
 int htp_hdr_keycb(http_parser *htp, const char *data, size_t len) {
   auto upstream = static_cast<HttpsUpstream *>(htp->data);
   auto downstream = upstream->get_downstream();
-  if (downstream->get_request_state() != Downstream::INITIAL) {
-    // ignore trailers
-    return 0;
-  }
-  if (downstream->get_request_header_key_prev()) {
-    downstream->append_last_request_header_key(data, len);
+  if (downstream->get_request_state() == Downstream::INITIAL) {
+    if (downstream->get_request_header_key_prev()) {
+      downstream->append_last_request_header_key(data, len);
+    } else {
+      downstream->add_request_header(std::string(data, len), "");
+    }
   } else {
-    downstream->add_request_header(std::string(data, len), "");
+    // trailer part
+    if (downstream->get_request_trailer_key_prev()) {
+      downstream->append_last_request_trailer_key(data, len);
+    } else {
+      downstream->add_request_trailer(std::string(data, len), "");
+    }
   }
   if (downstream->get_request_headers_sum() > Downstream::MAX_HEADERS_SUM) {
     if (LOG_ENABLED(INFO)) {
@@ -107,14 +112,18 @@ namespace {
 int htp_hdr_valcb(http_parser *htp, const char *data, size_t len) {
   auto upstream = static_cast<HttpsUpstream *>(htp->data);
   auto downstream = upstream->get_downstream();
-  if (downstream->get_request_state() != Downstream::INITIAL) {
-    // ignore trailers
-    return 0;
-  }
-  if (downstream->get_request_header_key_prev()) {
-    downstream->set_last_request_header_value(std::string(data, len));
+  if (downstream->get_request_state() == Downstream::INITIAL) {
+    if (downstream->get_request_header_key_prev()) {
+      downstream->set_last_request_header_value(data, len);
+    } else {
+      downstream->append_last_request_header_value(data, len);
+    }
   } else {
-    downstream->append_last_request_header_value(data, len);
+    if (downstream->get_request_trailer_key_prev()) {
+      downstream->set_last_request_trailer_value(data, len);
+    } else {
+      downstream->append_last_request_trailer_value(data, len);
+    }
   }
   if (downstream->get_request_headers_sum() > Downstream::MAX_HEADERS_SUM) {
     if (LOG_ENABLED(INFO)) {