diff --git a/src/shrpx_quic.cc b/src/shrpx_quic.cc
index 0e3fbb17..360b61c0 100644
--- a/src/shrpx_quic.cc
+++ b/src/shrpx_quic.cc
@@ -45,6 +45,10 @@
 
 using namespace nghttp2;
 
+bool operator==(const ngtcp2_cid &lhs, const ngtcp2_cid &rhs) {
+  return ngtcp2_cid_eq(&lhs, &rhs);
+}
+
 namespace shrpx {
 
 ngtcp2_tstamp quic_timestamp() {
diff --git a/src/shrpx_quic.h b/src/shrpx_quic.h
index 94483194..66254a91 100644
--- a/src/shrpx_quic.h
+++ b/src/shrpx_quic.h
@@ -29,8 +29,30 @@
 
 #include <stdint.h>
 
+#include <functional>
+
 #include <ngtcp2/ngtcp2.h>
 
+namespace std {
+template <> struct hash<ngtcp2_cid> {
+  std::size_t operator()(const ngtcp2_cid &cid) const noexcept {
+    // FNV-1a 64bits variant
+    constexpr uint64_t basis = 0xCBF29CE484222325ULL;
+    const uint8_t *p = cid.data, *end = cid.data + cid.datalen;
+    uint64_t h = basis;
+
+    for (; p != end;) {
+      h ^= *p++;
+      h *= basis;
+    }
+
+    return static_cast<size_t>(h);
+  }
+};
+} // namespace std
+
+bool operator==(const ngtcp2_cid &lhs, const ngtcp2_cid &rhs);
+
 namespace shrpx {
 
 struct UpstreamAddr;
diff --git a/src/shrpx_quic_connection_handler.cc b/src/shrpx_quic_connection_handler.cc
index f583738d..1b21513d 100644
--- a/src/shrpx_quic_connection_handler.cc
+++ b/src/shrpx_quic_connection_handler.cc
@@ -32,7 +32,6 @@
 #include "shrpx_worker.h"
 #include "shrpx_client_handler.h"
 #include "shrpx_log.h"
-#include "shrpx_quic.h"
 #include "shrpx_http3_upstream.h"
 #include "shrpx_connection_handler.h"
 
@@ -43,18 +42,6 @@ QUICConnectionHandler::QUICConnectionHandler(Worker *worker)
 
 QUICConnectionHandler::~QUICConnectionHandler() {}
 
-namespace {
-std::string make_cid_key(const uint8_t *dcid, size_t dcidlen) {
-  return std::string{dcid, dcid + dcidlen};
-}
-} // namespace
-
-namespace {
-std::string make_cid_key(const ngtcp2_cid *cid) {
-  return make_cid_key(cid->data, cid->datalen);
-}
-} // namespace
-
 int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
                                          const Address &remote_addr,
                                          const Address &local_addr,
@@ -80,7 +67,8 @@ int QUICConnectionHandler::handle_packet(const UpstreamAddr *faddr,
 
   auto config = get_config();
 
-  auto dcid_key = make_cid_key(dcid, dcidlen);
+  ngtcp2_cid dcid_key;
+  ngtcp2_cid_init(&dcid_key, dcid, dcidlen);
 
   auto conn_handler = worker_->get_connection_handler();
 
@@ -462,24 +450,22 @@ int QUICConnectionHandler::send_connection_close(
 
 void QUICConnectionHandler::add_connection_id(const ngtcp2_cid *cid,
                                               ClientHandler *handler) {
-  auto key = make_cid_key(cid);
-  connections_.emplace(key, handler);
+  connections_.emplace(*cid, handler);
 }
 
 void QUICConnectionHandler::remove_connection_id(const ngtcp2_cid *cid) {
-  auto key = make_cid_key(cid);
-  connections_.erase(key);
+  connections_.erase(*cid);
 }
 
 void QUICConnectionHandler::add_close_wait(CloseWait *cw) {
   for (auto &cid : cw->scids) {
-    close_waits_.emplace(make_cid_key(&cid), cw);
+    close_waits_.emplace(cid, cw);
   }
 }
 
 void QUICConnectionHandler::remove_close_wait(const CloseWait *cw) {
   for (auto &cid : cw->scids) {
-    close_waits_.erase(make_cid_key(&cid));
+    close_waits_.erase(cid);
   }
 }
 
diff --git a/src/shrpx_quic_connection_handler.h b/src/shrpx_quic_connection_handler.h
index b1888ef7..84530173 100644
--- a/src/shrpx_quic_connection_handler.h
+++ b/src/shrpx_quic_connection_handler.h
@@ -36,6 +36,7 @@
 
 #include <ev.h>
 
+#include "shrpx_quic.h"
 #include "network.h"
 
 using namespace nghttp2;
@@ -127,8 +128,8 @@ public:
 
 private:
   Worker *worker_;
-  std::unordered_map<std::string, ClientHandler *> connections_;
-  std::unordered_map<std::string, CloseWait *> close_waits_;
+  std::unordered_map<ngtcp2_cid, ClientHandler *> connections_;
+  std::unordered_map<ngtcp2_cid, CloseWait *> close_waits_;
 };
 
 } // namespace shrpx