diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index 8d02d740..415df864 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -292,11 +292,12 @@ int ClientHandler::write_tls() {
 #ifdef ENABLE_HTTP3
 int ClientHandler::read_quic(const UpstreamAddr *faddr,
                              const Address &remote_addr,
-                             const Address &local_addr, const uint8_t *data,
+                             const Address &local_addr,
+                             const ngtcp2_pkt_info &pi, const uint8_t *data,
                              size_t datalen) {
   auto upstream = static_cast<Http3Upstream *>(upstream_.get());
 
-  return upstream->on_read(faddr, remote_addr, local_addr, data, datalen);
+  return upstream->on_read(faddr, remote_addr, local_addr, pi, data, datalen);
 }
 
 int ClientHandler::write_quic() { return upstream_->on_write(); }
diff --git a/src/shrpx_client_handler.h b/src/shrpx_client_handler.h
index f20adc92..c2c50c0b 100644
--- a/src/shrpx_client_handler.h
+++ b/src/shrpx_client_handler.h
@@ -149,7 +149,8 @@ public:
 #ifdef ENABLE_HTTP3
   void setup_http3_upstream(std::unique_ptr<Http3Upstream> &&upstream);
   int read_quic(const UpstreamAddr *faddr, const Address &remote_addr,
-                const Address &local_addr, const uint8_t *data, size_t datalen);
+                const Address &local_addr, const ngtcp2_pkt_info &pi,
+                const uint8_t *data, size_t datalen);
   int write_quic();
 #endif // ENABLE_HTTP3
 
diff --git a/src/shrpx_connection_handler.cc b/src/shrpx_connection_handler.cc
index cf45f508..4f216a5c 100644
--- a/src/shrpx_connection_handler.cc
+++ b/src/shrpx_connection_handler.cc
@@ -1017,12 +1017,10 @@ void ConnectionHandler::set_enable_acceptor_on_ocsp_completion(bool f) {
 }
 
 #ifdef ENABLE_HTTP3
-int ConnectionHandler::forward_quic_packet(const UpstreamAddr *faddr,
-                                           const Address &remote_addr,
-                                           const Address &local_addr,
-                                           const uint8_t *cid_prefix,
-                                           const uint8_t *data,
-                                           size_t datalen) {
+int ConnectionHandler::forward_quic_packet(
+    const UpstreamAddr *faddr, const Address &remote_addr,
+    const Address &local_addr, const ngtcp2_pkt_info &pi,
+    const uint8_t *cid_prefix, const uint8_t *data, size_t datalen) {
   assert(!get_config()->single_thread);
 
   for (auto &worker : workers_) {
@@ -1034,7 +1032,7 @@ int ConnectionHandler::forward_quic_packet(const UpstreamAddr *faddr,
     WorkerEvent wev{};
     wev.type = WorkerEventType::QUIC_PKT_FORWARD;
     wev.quic_pkt = std::make_unique<QUICPacket>(faddr->index, remote_addr,
-                                                local_addr, data, datalen);
+                                                local_addr, pi, data, datalen);
 
     worker->send(std::move(wev));
 
@@ -1111,10 +1109,11 @@ void ConnectionHandler::set_quic_lingering_worker_processes(
 
 int ConnectionHandler::forward_quic_packet_to_lingering_worker_process(
     QUICLingeringWorkerProcess *quic_lwp, const Address &remote_addr,
-    const Address &local_addr, const uint8_t *data, size_t datalen) {
+    const Address &local_addr, const ngtcp2_pkt_info &pi, const uint8_t *data,
+    size_t datalen) {
   std::array<uint8_t, 512> header;
 
-  assert(header.size() >= 1 + 1 + 1 + sizeof(sockaddr_storage) * 2);
+  assert(header.size() >= 1 + 1 + 1 + 1 + sizeof(sockaddr_storage) * 2);
   assert(remote_addr.len > 0);
   assert(local_addr.len > 0);
 
@@ -1127,6 +1126,7 @@ int ConnectionHandler::forward_quic_packet_to_lingering_worker_process(
   *p++ = static_cast<uint8_t>(local_addr.len - 1);
   p = std::copy_n(reinterpret_cast<const uint8_t *>(&local_addr.su),
                   local_addr.len, p);
+  *p++ = pi.ecn;
 
   iovec msg_iov[] = {
       {
@@ -1185,14 +1185,14 @@ int ConnectionHandler::quic_ipc_read() {
     return 0;
   }
 
-  size_t len = 1 + 1 + 1;
+  size_t len = 1 + 1 + 1 + 1;
 
   // Wire format:
-  // TYPE(1) REMOTE_ADDRLEN(1) REMOTE_ADDR(N) LOCAL_ADDRLEN(1) REMOTE_ADDR(N)
-  // DGRAM_PAYLAOD(N)
+  // TYPE(1) REMOTE_ADDRLEN(1) REMOTE_ADDR(N) LOCAL_ADDRLEN(1) LOCAL_ADDR(N)
+  // ECN(1) DGRAM_PAYLOAD(N)
   //
-  // When encoding, REMOTE_ADDRLEN and LOCAL_ADDRLEN is decremented by
-  // 1.
+  // When encoding, REMOTE_ADDRLEN and LOCAL_ADDRLEN are decremented
+  // by 1.
   if (static_cast<size_t>(nread) < len) {
     return 0;
   }
@@ -1249,6 +1249,8 @@ int ConnectionHandler::quic_ipc_read() {
 
   p += local_addrlen;
 
+  pkt->pi.ecn = *p++;
+
   auto datalen = nread - (p - buf.data());
 
   pkt->data.assign(p, p + datalen);
@@ -1288,7 +1290,8 @@ int ConnectionHandler::quic_ipc_read() {
 
     // Ignore return value
     quic_conn_handler->handle_packet(faddr, pkt->remote_addr, pkt->local_addr,
-                                     pkt->data.data(), pkt->data.size());
+                                     pkt->pi, pkt->data.data(),
+                                     pkt->data.size());
 
     return 0;
   }
diff --git a/src/shrpx_connection_handler.h b/src/shrpx_connection_handler.h
index 8bbf99c1..8a515e4b 100644
--- a/src/shrpx_connection_handler.h
+++ b/src/shrpx_connection_handler.h
@@ -196,8 +196,9 @@ public:
   const std::vector<SSL_CTX *> &get_quic_indexed_ssl_ctx(size_t idx) const;
 
   int forward_quic_packet(const UpstreamAddr *faddr, const Address &remote_addr,
-                          const Address &local_addr, const uint8_t *cid_prefix,
-                          const uint8_t *data, size_t datalen);
+                          const Address &local_addr, const ngtcp2_pkt_info &pi,
+                          const uint8_t *cid_prefix, const uint8_t *data,
+                          size_t datalen);
 
   void set_quic_keying_materials(std::shared_ptr<QUICKeyingMaterials> qkms);
   const std::shared_ptr<QUICKeyingMaterials> &get_quic_keying_materials() const;
@@ -218,7 +219,8 @@ public:
 
   int forward_quic_packet_to_lingering_worker_process(
       QUICLingeringWorkerProcess *quic_lwp, const Address &remote_addr,
-      const Address &local_addr, const uint8_t *data, size_t datalen);
+      const Address &local_addr, const ngtcp2_pkt_info &pi, const uint8_t *data,
+      size_t datalen);
 
   void set_quic_ipc_fd(int fd);
 
diff --git a/src/shrpx_http3_upstream.cc b/src/shrpx_http3_upstream.cc
index 681acfe3..de3704f0 100644
--- a/src/shrpx_http3_upstream.cc
+++ b/src/shrpx_http3_upstream.cc
@@ -1632,10 +1632,9 @@ void Http3Upstream::cancel_premature_downstream(
 
 int Http3Upstream::on_read(const UpstreamAddr *faddr,
                            const Address &remote_addr,
-                           const Address &local_addr, const uint8_t *data,
-                           size_t datalen) {
+                           const Address &local_addr, const ngtcp2_pkt_info &pi,
+                           const uint8_t *data, size_t datalen) {
   int rv;
-  ngtcp2_pkt_info pi{};
 
   auto path = ngtcp2_path{
       {
diff --git a/src/shrpx_http3_upstream.h b/src/shrpx_http3_upstream.h
index b2935afc..5df95283 100644
--- a/src/shrpx_http3_upstream.h
+++ b/src/shrpx_http3_upstream.h
@@ -92,7 +92,8 @@ public:
            const ngtcp2_cid *odcid, const uint8_t *token, size_t tokenlen);
 
   int on_read(const UpstreamAddr *faddr, const Address &remote_addr,
-              const Address &local_addr, const uint8_t *data, size_t datalen);
+              const Address &local_addr, const ngtcp2_pkt_info &pi,
+              const uint8_t *data, size_t datalen);
 
   int write_streams();
 
diff --git a/src/shrpx_quic_connection_handler.cc b/src/shrpx_quic_connection_handler.cc
index 325e6957..38249e29 100644
--- a/src/shrpx_quic_connection_handler.cc
+++ b/src/shrpx_quic_connection_handler.cc
@@ -61,6 +61,7 @@ QUICConnectionHandler::~QUICConnectionHandler() {
 int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
                                          const Address &remote_addr,
                                          const Address &local_addr,
+                                         const ngtcp2_pkt_info &pi,
                                          const uint8_t *data, size_t datalen) {
   int rv;
   uint32_t version;
@@ -98,7 +99,7 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
     if (cwit != std::end(close_waits_)) {
       auto cw = (*cwit).second;
 
-      cw->handle_packet(faddr, remote_addr, local_addr, data, datalen);
+      cw->handle_packet(faddr, remote_addr, local_addr, pi, data, datalen);
 
       return 0;
     }
@@ -115,7 +116,7 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
         if (cwit != std::end(close_waits_)) {
           auto cw = (*cwit).second;
 
-          cw->handle_packet(faddr, remote_addr, local_addr, data, datalen);
+          cw->handle_packet(faddr, remote_addr, local_addr, pi, data, datalen);
 
           return 0;
         }
@@ -147,7 +148,7 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
                 decrypted_dcid.data(), decrypted_dcid.size());
         if (quic_lwp) {
           if (conn_handler->forward_quic_packet_to_lingering_worker_process(
-                  quic_lwp, remote_addr, local_addr, data, datalen) == 0) {
+                  quic_lwp, remote_addr, local_addr, pi, data, datalen) == 0) {
             return 0;
           }
 
@@ -310,7 +311,7 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
                       std::begin(decrypted_dcid) + SHRPX_QUIC_CID_PREFIXLEN,
                       worker_->get_cid_prefix())) {
         if (conn_handler->forward_quic_packet(faddr, remote_addr, local_addr,
-                                              decrypted_dcid.data(), data,
+                                              pi, decrypted_dcid.data(), data,
                                               datalen) == 0) {
           return 0;
         }
@@ -333,7 +334,8 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
     handler = (*it).second;
   }
 
-  if (handler->read_quic(faddr, remote_addr, local_addr, data, datalen) != 0) {
+  if (handler->read_quic(faddr, remote_addr, local_addr, pi, data, datalen) !=
+      0) {
     delete handler;
     return 0;
   }
@@ -708,7 +710,8 @@ CloseWait::~CloseWait() {
 
 int CloseWait::handle_packet(const UpstreamAddr *faddr,
                              const Address &remote_addr,
-                             const Address &local_addr, const uint8_t *data,
+                             const Address &local_addr,
+                             const ngtcp2_pkt_info &pi, const uint8_t *data,
                              size_t datalen) {
   if (pkt.empty()) {
     return 0;
diff --git a/src/shrpx_quic_connection_handler.h b/src/shrpx_quic_connection_handler.h
index 39c1b7d2..48faba77 100644
--- a/src/shrpx_quic_connection_handler.h
+++ b/src/shrpx_quic_connection_handler.h
@@ -55,8 +55,8 @@ struct CloseWait {
   ~CloseWait();
 
   int handle_packet(const UpstreamAddr *faddr, const Address &remote_addr,
-                    const Address &local_addr, const uint8_t *data,
-                    size_t datalen);
+                    const Address &local_addr, const ngtcp2_pkt_info &pi,
+                    const uint8_t *data, size_t datalen);
 
   Worker *worker;
   // Source Connection IDs of the connection.
@@ -82,8 +82,8 @@ public:
   QUICConnectionHandler(Worker *worker);
   ~QUICConnectionHandler();
   int handle_packet(const UpstreamAddr *faddr, const Address &remote_addr,
-                    const Address &local_addr, const uint8_t *data,
-                    size_t datalen);
+                    const Address &local_addr, const ngtcp2_pkt_info &pi,
+                    const uint8_t *data, size_t datalen);
   // Send Retry packet.  |ini_dcid| is the destination Connection ID
   // which appeared in Client Initial packet and its length is
   // |dcidlen|.  |ini_scid| is the source Connection ID which appeared
diff --git a/src/shrpx_quic_listener.cc b/src/shrpx_quic_listener.cc
index b06ec557..d22045d6 100644
--- a/src/shrpx_quic_listener.cc
+++ b/src/shrpx_quic_listener.cc
@@ -59,7 +59,8 @@ void QUICListener::on_read() {
   msg.msg_iov = &msg_iov;
   msg.msg_iovlen = 1;
 
-  uint8_t msg_ctrl[CMSG_SPACE(sizeof(in6_pktinfo))];
+  uint8_t
+      msg_ctrl[CMSG_SPACE(sizeof(uint8_t)) + CMSG_SPACE(sizeof(in6_pktinfo))];
   msg.msg_control = msg_ctrl;
 
   auto quic_conn_handler = worker_->get_quic_connection_handler();
@@ -83,11 +84,16 @@ void QUICListener::on_read() {
 
     util::set_port(local_addr, faddr_->port);
 
+    ngtcp2_pkt_info pi{
+        .ecn = util::msghdr_get_ecn(&msg, su.storage.ss_family),
+    };
+
     if (LOG_ENABLED(INFO)) {
       LOG(INFO) << "QUIC received packet: local="
                 << util::to_numeric_addr(&local_addr)
                 << " remote=" << util::to_numeric_addr(&su.sa, msg.msg_namelen)
-                << " " << nread << " bytes";
+                << " ecn=" << log::hex << pi.ecn << log::dec << " " << nread
+                << " bytes";
     }
 
     if (nread == 0) {
@@ -98,7 +104,7 @@ void QUICListener::on_read() {
     remote_addr.su = su;
     remote_addr.len = msg.msg_namelen;
 
-    quic_conn_handler->handle_packet(faddr_, remote_addr, local_addr,
+    quic_conn_handler->handle_packet(faddr_, remote_addr, local_addr, pi,
                                      buf.data(), nread);
   }
 }
diff --git a/src/shrpx_worker.cc b/src/shrpx_worker.cc
index a0107cc9..89423537 100644
--- a/src/shrpx_worker.cc
+++ b/src/shrpx_worker.cc
@@ -554,7 +554,7 @@ void Worker::process_events() {
 
     quic_conn_handler_.handle_packet(
         faddr, wev.quic_pkt->remote_addr, wev.quic_pkt->local_addr,
-        wev.quic_pkt->data.data(), wev.quic_pkt->data.size());
+        wev.quic_pkt->pi, wev.quic_pkt->data.data(), wev.quic_pkt->data.size());
 
     break;
   }
@@ -844,7 +844,7 @@ int Worker::create_quic_server_socket(UpstreamAddr &faddr) {
       }
     }
 
-    // TODO Enable ECN
+    util::fd_set_recv_ecn(fd, faddr.family);
 
     if (bind(fd, rp->ai_addr, rp->ai_addrlen) == -1) {
       auto error = errno;
diff --git a/src/shrpx_worker.h b/src/shrpx_worker.h
index 8cf40e97..724c56ed 100644
--- a/src/shrpx_worker.h
+++ b/src/shrpx_worker.h
@@ -258,15 +258,18 @@ struct WorkerStat {
 #ifdef ENABLE_HTTP3
 struct QUICPacket {
   QUICPacket(size_t upstream_addr_index, const Address &remote_addr,
-             const Address &local_addr, const uint8_t *data, size_t datalen)
+             const Address &local_addr, const ngtcp2_pkt_info &pi,
+             const uint8_t *data, size_t datalen)
       : upstream_addr_index{upstream_addr_index},
         remote_addr{remote_addr},
         local_addr{local_addr},
+        pi{pi},
         data{data, data + datalen} {}
-  QUICPacket() {}
+  QUICPacket() : upstream_addr_index{}, remote_addr{}, local_addr{}, pi{} {}
   size_t upstream_addr_index;
   Address remote_addr;
   Address local_addr;
+  ngtcp2_pkt_info pi;
   std::vector<uint8_t> data;
 };
 #endif // ENABLE_HTTP3
diff --git a/src/util.cc b/src/util.cc
index 213989e4..eb70bbb3 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -1722,6 +1722,54 @@ int msghdr_get_local_addr(Address &dest, msghdr *msg, int family) {
 
   return -1;
 }
+
+unsigned int msghdr_get_ecn(msghdr *msg, int family) {
+  switch (family) {
+  case AF_INET:
+    for (auto cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+      if (cmsg->cmsg_level == IPPROTO_IP && cmsg->cmsg_type == IP_TOS &&
+          cmsg->cmsg_len) {
+        return *reinterpret_cast<uint8_t *>(CMSG_DATA(cmsg));
+      }
+    }
+
+    return 0;
+  case AF_INET6:
+    for (auto cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+      if (cmsg->cmsg_level == IPPROTO_IPV6 && cmsg->cmsg_type == IPV6_TCLASS &&
+          cmsg->cmsg_len) {
+        return *reinterpret_cast<uint8_t *>(CMSG_DATA(cmsg));
+      }
+    }
+
+    return 0;
+  }
+
+  return 0;
+}
+
+int fd_set_recv_ecn(int fd, int family) {
+  unsigned int tos = 1;
+
+  switch (family) {
+  case AF_INET:
+    if (setsockopt(fd, IPPROTO_IP, IP_RECVTOS, &tos,
+                   static_cast<socklen_t>(sizeof(tos))) == -1) {
+      return -1;
+    }
+
+    return 0;
+  case AF_INET6:
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVTCLASS, &tos,
+                   static_cast<socklen_t>(sizeof(tos))) == -1) {
+      return -1;
+    }
+
+    return 0;
+  }
+
+  return -1;
+}
 #endif // ENABLE_HTTP3
 
 } // namespace util
diff --git a/src/util.h b/src/util.h
index 4d5cef37..e154b6ed 100644
--- a/src/util.h
+++ b/src/util.h
@@ -918,6 +918,10 @@ int daemonize(int nochdir, int noclose);
 
 #ifdef ENABLE_HTTP3
 int msghdr_get_local_addr(Address &dest, msghdr *msg, int family);
+
+unsigned int msghdr_get_ecn(msghdr *msg, int family);
+
+int fd_set_recv_ecn(int fd, int family);
 #endif // ENABLE_HTTP3
 
 } // namespace util