diff --git a/CMakeLists.txt b/CMakeLists.txt
index eab2a177..579d0365 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -448,6 +448,10 @@ foreach(name
   configure_file("${name}.in" "${name}" @ONLY)
 endforeach()
 
+if(APPLE)
+  add_definitions(-D__APPLE_USE_RFC_3542)
+endif()
+
 include_directories(
   "${CMAKE_CURRENT_BINARY_DIR}" # for config.h
 )
diff --git a/configure.ac b/configure.ac
index def91ae8..37256518 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,6 +107,11 @@ AC_ARG_ENABLE([lib-only],
                     [Build libnghttp2 only.  This is a short hand for --disable-app --disable-examples --disable-hpack-tools --disable-python-bindings])],
     [request_lib_only=$enableval], [request_lib_only=no])
 
+AC_ARG_ENABLE([http3],
+    [AS_HELP_STRING([--enable-http3],
+                    [(EXPERIMENTAL) Enable HTTP/3.  This requires ngtcp2, nghttp3, and a custom OpenSSL.])],
+    [request_http3=$enableval], [request_http3=no])
+
 AC_ARG_WITH([libxml2],
     [AS_HELP_STRING([--with-libxml2],
                     [Use libxml2 [default=check]])],
@@ -172,6 +177,16 @@ AC_ARG_WITH([cython],
                     [Use cython in given PATH])],
     [cython_path=$withval], [])
 
+AC_ARG_WITH([libngtcp2],
+    [AS_HELP_STRING([--with-libngtcp2],
+                    [Use libngtcp2 [default=check]])],
+    [request_libngtcp2=$withval], [request_libngtcp2=check])
+
+AC_ARG_WITH([libnghttp3],
+    [AS_HELP_STRING([--with-libnghttp3],
+                    [Use libnghttp3 [default=check]])],
+    [request_libnghttp3=$withval], [request_libnghttp3=check])
+
 dnl Define variables
 AC_ARG_VAR([CYTHON], [the Cython executable])
 
@@ -334,6 +349,13 @@ case "$host_os" in
     ;;
 esac
 
+case "${build}" in
+  *-apple-darwin*)
+    EXTRA_DEFS="-D__APPLE_USE_RFC_3542"
+    AC_SUBST([EXTRA_DEFS])
+    ;;
+esac
+
 # zlib
 have_zlib=no
 if test "x${request_zlib}" != "xno"; then
@@ -455,26 +477,50 @@ if test "x${request_libcares}" = "xyes" &&
 fi
 
 # ngtcp2 (for src)
-PKG_CHECK_MODULES([LIBNGTCP2], [libngtcp2 >= 0.0.0], [have_libngtcp2=yes],
-                  [have_libngtcp2=no])
-if test "x${have_libngtcp2}" = "xno"; then
-  AC_MSG_NOTICE($LIBNGTCP2_PKG_ERRORS)
+have_libngtcp2=no
+if test "x${request_libngtcp2}" != "xno"; then
+  PKG_CHECK_MODULES([LIBNGTCP2], [libngtcp2 >= 0.0.0], [have_libngtcp2=yes],
+                    [have_libngtcp2=no])
+  if test "x${have_libngtcp2}" = "xno"; then
+    AC_MSG_NOTICE($LIBNGTCP2_PKG_ERRORS)
+  fi
+fi
+
+if test "x${request_libngtcp2}" = "xyes" &&
+   test "x${have_libngtcp2}" != "xyes"; then
+  AC_MSG_ERROR([libngtcp2 was requested (--with-libngtcp2) but not found])
 fi
 
 # ngtcp2_crypto_openssl (for src)
-PKG_CHECK_MODULES([LIBNGTCP2_CRYPTO_OPENSSL],
-                  [libngtcp2_crypto_openssl >= 0.0.0],
-                  [have_libngtcp2_crypto_openssl=yes],
-                  [have_libngtcp2_crypto_openssl=no])
-if test "x${have_libngtcp2_crypto_openssl}" = "xno"; then
-  AC_MSG_NOTICE($LIBNGTCP2_CRYPTO_OPENSSL_PKG_ERRORS)
+have_libngtcp2_crypto_openssl=no
+if test "x${request_libngtcp2}" != "xno"; then
+  PKG_CHECK_MODULES([LIBNGTCP2_CRYPTO_OPENSSL],
+                    [libngtcp2_crypto_openssl >= 0.0.0],
+                    [have_libngtcp2_crypto_openssl=yes],
+                    [have_libngtcp2_crypto_openssl=no])
+  if test "x${have_libngtcp2_crypto_openssl}" = "xno"; then
+    AC_MSG_NOTICE($LIBNGTCP2_CRYPTO_OPENSSL_PKG_ERRORS)
+  fi
+fi
+
+if test "x${request_libngtcp2}" = "xyes" &&
+   test "x${have_libngtcp2_crypto_openssl}" != "xyes"; then
+  AC_MSG_ERROR([libngtcp2_crypto_openssl was requested (--with-libngtcp2) but not found])
 fi
 
 # nghttp3 (for src)
-PKG_CHECK_MODULES([LIBNGHTTP3], [libnghttp3 >= 0.0.0], [have_libnghttp3=yes],
-                  [have_libnghttp3=no])
-if test "x${have_libnghttp3}" = "xno"; then
-  AC_MSG_NOTICE($LIBNGHTTP3_PKT_ERRORS)
+have_libnghttp3=no
+if test "x${request_libnghttp3}" != "xno"; then
+  PKG_CHECK_MODULES([LIBNGHTTP3], [libnghttp3 >= 0.0.0], [have_libnghttp3=yes],
+                    [have_libnghttp3=no])
+  if test "x${have_libnghttp3}" = "xno"; then
+    AC_MSG_NOTICE($LIBNGHTTP3_PKG_ERRORS)
+  fi
+fi
+
+if test "x${request_libnghttp3}" = "xyes" &&
+   test "x${have_libnghttp3}" != "xyes"; then
+  AC_MSG_ERROR([libnghttp3 was requested (--with-libnghttp3) but not found])
 fi
 
 # libevent_openssl (for examples)
@@ -621,6 +667,23 @@ fi
 
 AM_CONDITIONAL([ENABLE_APP], [ test "x${enable_app}" = "xyes" ])
 
+# Check HTTP/3 support
+enable_http3=no
+if test "x${request_http3}" != "xno" &&
+   test "x${have_libngtcp2}" = "xyes" &&
+   test "x${have_libngtcp2_crypto_openssl}" = "xyes" &&
+   test "x${have_libnghttp3}" = "xyes"; then
+  enable_http3=yes
+  AC_DEFINE([ENABLE_HTTP3], [1], [Define to 1 if HTTP/3 is enabled.])
+fi
+
+if test "x${request_http3}" = "xyes" &&
+   test "x${enable_http3}" != "xyes"; then
+  AC_MSG_ERROR([HTTP/3 was requested (--enable-http3) but dependencies are not met.])
+fi
+
+AM_CONDITIONAL([ENABLE_HTTP3], [ test "x${enable_http3}" = "xyes" ])
+
 enable_hpack_tools=no
 # HPACK tools requires jansson
 if test "x${request_hpack_tools}" != "xno" &&
@@ -1058,4 +1121,5 @@ AC_MSG_NOTICE([summary of build options:
       Examples:       ${enable_examples}
       Python bindings:${enable_python_bindings}
       Threading:      ${enable_threads}
+      HTTP/3 (EXPERIMENTAL): ${enable_http3}
 ])
diff --git a/src/Makefile.am b/src/Makefile.am
index 9226ed31..eb763fb6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -51,6 +51,7 @@ AM_CPPFLAGS = \
 	@LIBNGTCP2_CFLAGS@ \
 	@JANSSON_CFLAGS@ \
 	@ZLIB_CFLAGS@ \
+	@EXTRA_DEFS@ \
 	@DEFS@
 AM_LDFLAGS = @LIBTOOL_LDFLAGS@
 
@@ -103,10 +104,14 @@ h2load_SOURCES = util.cc util.h \
 	tls.cc tls.h \
 	h2load_session.h \
 	h2load_http2_session.cc h2load_http2_session.h \
-	h2load_http1_session.cc h2load_http1_session.h \
+	h2load_http1_session.cc h2load_http1_session.h
+
+if ENABLE_HTTP3
+h2load_SOURCES += \
 	h2load_http3_session.cc h2load_http3_session.h \
 	h2load_quic.cc h2load_quic.h \
 	quic.cc quic.h
+endif # ENABLE_HTTP3
 
 NGHTTPX_SRCS = \
 	util.cc util.h http2.cc http2.h timegm.c timegm.h base64.h \
@@ -153,12 +158,6 @@ NGHTTPX_SRCS = \
 	shrpx_dns_resolver.cc shrpx_dns_resolver.h \
 	shrpx_dual_dns_resolver.cc shrpx_dual_dns_resolver.h \
 	shrpx_dns_tracker.cc shrpx_dns_tracker.h \
-	shrpx_quic.cc shrpx_quic.h \
-	shrpx_quic_listener.cc shrpx_quic_listener.h \
-	shrpx_quic_connection_handler.cc shrpx_quic_connection_handler.h \
-	shrpx_http3_upstream.cc shrpx_http3_upstream.h \
-	http3.cc http3.h \
-	quic.cc quic.h \
 	buffer.h memchunk.h template.h allocator.h \
 	xsi_strerror.c xsi_strerror.h
 
@@ -171,6 +170,16 @@ NGHTTPX_SRCS += \
 	shrpx_mruby_module_response.cc shrpx_mruby_module_response.h
 endif # HAVE_MRUBY
 
+if ENABLE_HTTP3
+NGHTTPX_SRCS += \
+	shrpx_quic.cc shrpx_quic.h \
+	shrpx_quic_listener.cc shrpx_quic_listener.h \
+	shrpx_quic_connection_handler.cc shrpx_quic_connection_handler.h \
+	shrpx_http3_upstream.cc shrpx_http3_upstream.h \
+	http3.cc http3.h \
+	quic.cc quic.h
+endif # ENABLE_HTTP3
+
 noinst_LIBRARIES = libnghttpx.a
 libnghttpx_a_SOURCES = ${NGHTTPX_SRCS}
 libnghttpx_a_CPPFLAGS = ${AM_CPPFLAGS}
diff --git a/src/h2load.cc b/src/h2load.cc
index d08cff61..2b3f529b 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -50,14 +50,18 @@
 
 #include <openssl/err.h>
 
-#include <ngtcp2/ngtcp2.h>
+#ifdef ENABLE_HTTP3
+#  include <ngtcp2/ngtcp2.h>
+#endif // ENABLE_HTTP3
 
 #include "url-parser/url_parser.h"
 
 #include "h2load_http1_session.h"
 #include "h2load_http2_session.h"
-#include "h2load_http3_session.h"
-#include "h2load_quic.h"
+#ifdef ENABLE_HTTP3
+#  include "h2load_http3_session.h"
+#  include "h2load_quic.h"
+#endif // ENABLE_HTTP3
 #include "tls.h"
 #include "http2.h"
 #include "util.h"
@@ -141,8 +145,12 @@ bool Config::is_timing_based_mode() const { return (this->duration > 0); }
 bool Config::has_base_uri() const { return (!this->base_uri.empty()); }
 bool Config::rps_enabled() const { return this->rps > 0.0; }
 bool Config::is_quic() const {
+#ifdef ENABLE_HTTP3
   return !npn_list.empty() &&
          (npn_list[0] == NGHTTP3_ALPN_H3 || npn_list[0] == "\x5h3-29");
+#else  // !ENABLE_HTTP3
+  return false;
+#endif // !ENABLE_HTTP3
 }
 Config config;
 
@@ -435,7 +443,9 @@ Client::Client(uint32_t id, Worker *worker, size_t req_todo)
       cstat{},
       worker(worker),
       ssl(nullptr),
+#ifdef ENABLE_HTTP3
       quic{},
+#endif // ENABLE_HTTP3
       next_addr(config.addrs),
       current_addr(nullptr),
       reqidx(0),
@@ -478,16 +488,20 @@ Client::Client(uint32_t id, Worker *worker, size_t req_todo)
   ev_timer_init(&rps_watcher, rps_cb, 0., 0.);
   rps_watcher.data = this;
 
+#ifdef ENABLE_HTTP3
   ev_timer_init(&quic.pkt_timer, quic_pkt_timeout_cb, 0., 0.);
   quic.pkt_timer.data = this;
+#endif // ENABLE_HTTP3
 }
 
 Client::~Client() {
   disconnect();
 
+#ifdef ENABLE_HTTP3
   if (config.is_quic()) {
     quic_free();
   }
+#endif // ENABLE_HTTP3
 
   if (ssl) {
     SSL_free(ssl);
@@ -504,6 +518,7 @@ int Client::make_socket(addrinfo *addr) {
   int rv;
 
   if (config.is_quic()) {
+#ifdef ENABLE_HTTP3
     fd = util::create_nonblock_udp_socket(addr->ai_family);
     if (fd == -1) {
       return -1;
@@ -528,6 +543,7 @@ int Client::make_socket(addrinfo *addr) {
       std::cerr << "quic_init failed" << std::endl;
       return -1;
     }
+#endif // ENABLE_HTTP3
   } else {
     fd = util::create_nonblock_socket(addr->ai_family);
     if (fd == -1) {
@@ -614,10 +630,12 @@ int Client::connect() {
   ev_io_start(worker->loop, &wev);
 
   if (config.is_quic()) {
+#ifdef ENABLE_HTTP3
     ev_io_start(worker->loop, &rev);
 
     readfn = &Client::read_quic;
     writefn = &Client::write_quic;
+#endif // ENABLE_HTTP3
   } else {
     writefn = &Client::connected;
   }
@@ -676,11 +694,15 @@ void Client::fail() {
 void Client::disconnect() {
   record_client_end_time();
 
+#ifdef ENABLE_HTTP3
   if (config.is_quic()) {
     quic_close_connection();
   }
+#endif // ENABLE_HTTP3
 
+#ifdef ENABLE_HTTP3
   ev_timer_stop(worker->loop, &quic.pkt_timer);
+#endif // ENABLE_HTTP3
   ev_timer_stop(worker->loop, &conn_inactivity_watcher);
   ev_timer_stop(worker->loop, &conn_active_watcher);
   ev_timer_stop(worker->loop, &rps_watcher);
@@ -843,9 +865,11 @@ void Client::report_app_info() {
 }
 
 void Client::terminate_session() {
+#ifdef ENABLE_HTTP3
   if (config.is_quic()) {
     quic.close_requested = true;
   }
+#endif // ENABLE_HTTP3
   if (session) {
     session->terminate();
   }
@@ -1047,11 +1071,13 @@ int Client::connection_made() {
     if (next_proto) {
       auto proto = StringRef{next_proto, next_proto_len};
       if (config.is_quic()) {
+#ifdef ENABLE_HTTP3
         assert(session);
         if (!util::streq(StringRef{&NGHTTP3_ALPN_H3[1]}, proto) &&
             !util::streq_l("h3-29", proto)) {
           return -1;
         }
+#endif // ENABLE_HTTP3
       } else if (util::check_h2_is_selected(proto)) {
         session = std::make_unique<Http2Session>(this);
       } else if (util::streq(NGHTTP2_H1_1, proto)) {
@@ -1377,6 +1403,7 @@ int Client::write_tls() {
   return 0;
 }
 
+#ifdef ENABLE_HTTP3
 int Client::write_udp(const sockaddr *addr, socklen_t addrlen,
                       const uint8_t *data, size_t datalen, size_t gso_size) {
   iovec msg_iov;
@@ -1389,7 +1416,7 @@ int Client::write_udp(const sockaddr *addr, socklen_t addrlen,
   msg.msg_iov = &msg_iov;
   msg.msg_iovlen = 1;
 
-#ifdef UDP_SEGMENT
+#  ifdef UDP_SEGMENT
   std::array<uint8_t, CMSG_SPACE(sizeof(uint16_t))> msg_ctrl{};
   if (gso_size && datalen > gso_size) {
     msg.msg_control = msg_ctrl.data();
@@ -1401,7 +1428,7 @@ int Client::write_udp(const sockaddr *addr, socklen_t addrlen,
     cm->cmsg_len = CMSG_LEN(sizeof(uint16_t));
     *(reinterpret_cast<uint16_t *>(CMSG_DATA(cm))) = gso_size;
   }
-#endif // UDP_SEGMENT
+#  endif // UDP_SEGMENT
 
   auto nwrite = sendmsg(fd, &msg, 0);
   if (nwrite < 0) {
@@ -1414,6 +1441,7 @@ int Client::write_udp(const sockaddr *addr, socklen_t addrlen,
 
   return 0;
 }
+#endif // ENABLE_HTTP3
 
 void Client::record_request_time(RequestStat *req_stat) {
   req_stat->request_time = std::chrono::steady_clock::now();
@@ -2740,7 +2768,9 @@ int main(int argc, char **argv) {
           << "Warning: --qlog-file-base: only effective in quic, ignoring."
           << std::endl;
     } else {
+#ifdef ENABLE_HTTP3
       config.qlog_file_base = qlog_base;
+#endif // ENABLE_HTTP3
     }
   }
 
@@ -2764,8 +2794,10 @@ int main(int argc, char **argv) {
   SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
 
   if (config.is_quic()) {
+#ifdef ENABLE_HTTP3
     SSL_CTX_set_min_proto_version(ssl_ctx, TLS1_3_VERSION);
     SSL_CTX_set_max_proto_version(ssl_ctx, TLS1_3_VERSION);
+#endif // ENABLE_HTTP3
   } else if (nghttp2::tls::ssl_ctx_set_proto_versions(
                  ssl_ctx, nghttp2::tls::NGHTTP2_TLS_MIN_VERSION,
                  nghttp2::tls::NGHTTP2_TLS_MAX_VERSION) != 0) {
@@ -2780,12 +2812,14 @@ int main(int argc, char **argv) {
     exit(EXIT_FAILURE);
   }
 
+#if OPENSSL_1_1_1_API
   if (SSL_CTX_set_ciphersuites(ssl_ctx, config.tls13_ciphers.c_str()) == 0) {
     std::cerr << "SSL_CTX_set_ciphersuites with " << config.tls13_ciphers
               << " failed: " << ERR_error_string(ERR_get_error(), nullptr)
               << std::endl;
     exit(EXIT_FAILURE);
   }
+#endif // OPENSSL_1_1_1_API
 
   if (SSL_CTX_set1_groups_list(ssl_ctx, config.groups.c_str()) != 1) {
     std::cerr << "SSL_CTX_set1_groups_list failed" << std::endl;
@@ -2806,6 +2840,7 @@ int main(int argc, char **argv) {
   SSL_CTX_set_alpn_protos(ssl_ctx, proto_list.data(), proto_list.size());
 #endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
 
+#if OPENSSL_1_1_1_API
   auto keylog_filename = getenv("SSLKEYLOGFILE");
   if (keylog_filename) {
     keylog_file.open(keylog_filename, std::ios_base::app);
@@ -2813,6 +2848,7 @@ int main(int argc, char **argv) {
       SSL_CTX_set_keylog_callback(ssl_ctx, keylog_callback);
     }
   }
+#endif // OPENSSL_1_1_1_API
 
   std::string user_agent = "h2load nghttp2/" NGHTTP2_VERSION;
   Headers shared_nva;
@@ -3093,10 +3129,12 @@ traffic: )" << util::utos_funit(stats.bytes_total)
             << ") headers (space savings " << header_space_savings * 100
             << "%), " << util::utos_funit(stats.bytes_body) << "B ("
             << stats.bytes_body << R"() data)" << std::endl;
+#ifdef ENABLE_HTTP3
   if (config.is_quic()) {
     std::cout << "UDP datagram: " << stats.udp_dgram_sent << " sent, "
               << stats.udp_dgram_recv << " received" << std::endl;
   }
+#endif // ENABLE_HTTP3
   std::cout
       << R"(                     min         max         mean         sd        +/- sd
 time for request: )"
diff --git a/src/h2load.h b/src/h2load.h
index 061c776f..92c0e2ac 100644
--- a/src/h2load.h
+++ b/src/h2load.h
@@ -45,15 +45,19 @@
 
 #include <nghttp2/nghttp2.h>
 
-#include <ngtcp2/ngtcp2.h>
-#include <ngtcp2/ngtcp2_crypto.h>
+#ifdef ENABLE_HTTP3
+#  include <ngtcp2/ngtcp2.h>
+#  include <ngtcp2/ngtcp2_crypto.h>
+#endif // ENABLE_HTTP3
 
 #include <ev.h>
 
 #include <openssl/ssl.h>
 
 #include "http2.h"
-#include "quic.h"
+#ifdef ENABLE_HTTP3
+#  include "quic.h"
+#endif // ENABLE_HTTP3
 #include "memchunk.h"
 #include "template.h"
 
@@ -327,6 +331,7 @@ struct Client {
   std::function<int(Client &)> readfn, writefn;
   Worker *worker;
   SSL *ssl;
+#ifdef ENABLE_HTTP3
   struct {
     ev_timer pkt_timer;
     ngtcp2_conn *conn;
@@ -335,6 +340,7 @@ struct Client {
     bool close_requested;
     FILE *qlog_file;
   } quic;
+#endif // ENABLE_HTTP3
   ev_timer request_timeout_watcher;
   addrinfo *next_addr;
   // Address for the current address.  When try_new_connection() is
@@ -447,6 +453,7 @@ struct Client {
 
   void signal_write();
 
+#ifdef ENABLE_HTTP3
   // QUIC
   int quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
                 const sockaddr *remote_addr, socklen_t remote_addrlen);
@@ -475,6 +482,7 @@ struct Client {
   int quic_pkt_timeout();
   void quic_restart_pkt_timer();
   void quic_write_qlog(const void *data, size_t datalen);
+#endif // ENABLE_HTTP3
 };
 
 } // namespace h2load
diff --git a/src/shrpx.cc b/src/shrpx.cc
index 62c0abc0..a619fe77 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -1548,6 +1548,7 @@ void fill_default_config(Config *config) {
         downstreamconf.option, downstreamconf.encoder_dynamic_table_size);
   }
 
+#ifdef ENABLE_HTTP3
   auto &quicconf = config->quic;
   {
     quicconf.timeout.idle = 30_s;
@@ -1560,6 +1561,7 @@ void fill_default_config(Config *config) {
       exit(EXIT_FAILURE);
     }
   }
+#endif // ENABLE_HTTP3
 
   auto &loggingconf = config->logging;
   {
diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index 341566b6..d58c9a5f 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -51,7 +51,9 @@
 #include "shrpx_api_downstream_connection.h"
 #include "shrpx_health_monitor_downstream_connection.h"
 #include "shrpx_null_downstream_connection.h"
-#include "shrpx_http3_upstream.h"
+#ifdef ENABLE_HTTP3
+#  include "shrpx_http3_upstream.h"
+#endif // ENABLE_HTTP3
 #include "shrpx_log.h"
 #include "util.h"
 #include "template.h"
@@ -287,6 +289,7 @@ 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,
@@ -297,6 +300,7 @@ int ClientHandler::read_quic(const UpstreamAddr *faddr,
 }
 
 int ClientHandler::write_quic() { return upstream_->on_write(); }
+#endif // ENABLE_HTTP3
 
 int ClientHandler::upstream_noop() { return 0; }
 
@@ -509,12 +513,14 @@ void ClientHandler::setup_upstream_io_callback() {
   }
 }
 
+#ifdef ENABLE_HTTP3
 void ClientHandler::setup_http3_upstream(
     std::unique_ptr<Http3Upstream> &&upstream) {
   upstream_ = std::move(upstream);
   alpn_ = StringRef::from_lit("h3");
   write_ = &ClientHandler::write_quic;
 }
+#endif // ENABLE_HTTP3
 
 ClientHandler::~ClientHandler() {
   if (LOG_ENABLED(INFO)) {
diff --git a/src/shrpx_client_handler.h b/src/shrpx_client_handler.h
index ef467810..0c013973 100644
--- a/src/shrpx_client_handler.h
+++ b/src/shrpx_client_handler.h
@@ -53,7 +53,9 @@ class Downstream;
 struct WorkerStat;
 struct DownstreamAddrGroup;
 struct DownstreamAddr;
+#ifdef ENABLE_HTTP3
 class Http3Upstream;
+#endif // ENABLE_HTTP3
 
 class ClientHandler {
 public:
@@ -71,9 +73,6 @@ public:
   int read_tls();
   int write_tls();
 
-  int read_quic(const UpstreamAddr *faddr, const Address &remote_addr,
-                const Address &local_addr, const uint8_t *data, size_t datalen);
-
   int upstream_noop();
   int upstream_read();
   int upstream_http2_connhd_read();
@@ -147,8 +146,12 @@ public:
 
   void setup_upstream_io_callback();
 
+#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);
   int write_quic();
+#endif // ENABLE_HTTP3
 
   // Returns string suitable for use in "by" parameter of Forwarded
   // header field.
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index 8742ad6a..c3eb218a 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -821,7 +821,11 @@ int parse_upstream_params(UpstreamParams &out, const StringRef &src_params) {
     } else if (util::strieq_l("proxyproto", param)) {
       out.proxyproto = true;
     } else if (util::strieq_l("quic", param)) {
+#ifdef ENABLE_HTTP3
       out.quic = true;
+#else  // !ENABLE_HTTP3
+      LOG(ERROR) << "quic: QUIC is disabled at compile time";
+#endif // !ENABLE_HTTP3
     } else if (!param.empty()) {
       LOG(ERROR) << "frontend: " << param << ": unknown keyword";
       return -1;
@@ -2674,8 +2678,12 @@ int parse_config(Config *config, int optid, const StringRef &opt,
       apiconf.enabled = true;
     }
 
+#ifdef ENABLE_HTTP3
     auto &addrs = params.quic ? config->conn.quic_listener.addrs
                               : config->conn.listener.addrs;
+#else  // !ENABLE_HTTP3
+    auto &addrs = config->conn.listener.addrs;
+#endif // !ENABLE_HTTP3
 
     if (util::istarts_with(optarg, SHRPX_UNIX_PATH_PREFIX)) {
       auto path = std::begin(optarg) + SHRPX_UNIX_PATH_PREFIX.size();
diff --git a/src/shrpx_config.h b/src/shrpx_config.h
index 291e25e6..d3a22baa 100644
--- a/src/shrpx_config.h
+++ b/src/shrpx_config.h
@@ -704,6 +704,7 @@ struct TLSConfig {
   bool no_postpone_early_data;
 };
 
+#ifdef ENABLE_HTTP3
 struct QUICConfig {
   struct {
     std::array<uint8_t, 32> secret;
@@ -715,6 +716,7 @@ struct QUICConfig {
     bool log;
   } debug;
 };
+#endif // ENABLE_HTTP3
 
 // custom error page
 struct ErrorPage {
@@ -921,9 +923,11 @@ struct ConnectionConfig {
     int fastopen;
   } listener;
 
+#ifdef ENABLE_HTTP3
   struct {
     std::vector<UpstreamAddr> addrs;
   } quic_listener;
+#endif // ENABLE_HTTP3
 
   struct {
     struct {
@@ -968,7 +972,9 @@ struct Config {
         http{},
         http2{},
         tls{},
+#ifdef ENABLE_HTTP3
         quic{},
+#endif // ENABLE_HTTP3
         logging{},
         conn{},
         api{},
@@ -986,7 +992,8 @@ struct Config {
         single_process{false},
         single_thread{false},
         ignore_per_pattern_mruby_error{false},
-        ev_loop_flags{0} {}
+        ev_loop_flags{0} {
+  }
   ~Config();
 
   Config(Config &&) = delete;
@@ -1002,7 +1009,9 @@ struct Config {
   HttpConfig http;
   Http2Config http2;
   TLSConfig tls;
+#ifdef ENABLE_HTTP3
   QUICConfig quic;
+#endif // ENABLE_HTTP3
   LoggingConfig logging;
   ConnectionConfig conn;
   APIConfig api;
diff --git a/src/shrpx_connection_handler.cc b/src/shrpx_connection_handler.cc
index 03f74594..39ea08cd 100644
--- a/src/shrpx_connection_handler.cc
+++ b/src/shrpx_connection_handler.cc
@@ -156,6 +156,7 @@ ConnectionHandler::~ConnectionHandler() {
   ev_timer_stop(loop_, &ocsp_timer_);
   ev_timer_stop(loop_, &disable_acceptor_timer_);
 
+#ifdef ENABLE_HTTP3
   for (auto ssl_ctx : quic_all_ssl_ctx_) {
     if (ssl_ctx == nullptr) {
       continue;
@@ -166,6 +167,7 @@ ConnectionHandler::~ConnectionHandler() {
     delete tls_ctx_data;
     SSL_CTX_free(ssl_ctx);
   }
+#endif // ENABLE_HTTP3
 
   for (auto ssl_ctx : all_ssl_ctx_) {
     auto tls_ctx_data =
@@ -221,14 +223,16 @@ int ConnectionHandler::create_single_worker() {
 #endif // HAVE_NEVERBLEED
   );
 
+#ifdef ENABLE_HTTP3
   quic_cert_tree_ = tls::create_cert_lookup_tree();
   auto quic_sv_ssl_ctx = tls::setup_quic_server_ssl_context(
       quic_all_ssl_ctx_, quic_indexed_ssl_ctx_, quic_cert_tree_.get()
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
                                                     ,
       nb_
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
   );
+#endif // ENABLE_HTTP3
 
   auto cl_ssl_ctx = tls::setup_downstream_client_ssl_context(
 #ifdef HAVE_NEVERBLEED
@@ -238,7 +242,9 @@ int ConnectionHandler::create_single_worker() {
 
   if (cl_ssl_ctx) {
     all_ssl_ctx_.push_back(cl_ssl_ctx);
+#ifdef ENABLE_HTTP3
     quic_all_ssl_ctx_.push_back(nullptr);
+#endif // ENABLE_HTTP3
   }
 
   auto config = get_config();
@@ -255,22 +261,29 @@ int ConnectionHandler::create_single_worker() {
           tlsconf.cacert, memcachedconf.cert_file,
           memcachedconf.private_key_file, nullptr);
       all_ssl_ctx_.push_back(session_cache_ssl_ctx);
+#ifdef ENABLE_HTTP3
       quic_all_ssl_ctx_.push_back(nullptr);
+#endif // ENABLE_HTTP3
     }
   }
 
   single_worker_ = std::make_unique<Worker>(
       loop_, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx, cert_tree_.get(),
-      quic_sv_ssl_ctx, quic_cert_tree_.get(), ticket_keys_, this,
-      config->conn.downstream);
+#ifdef ENABLE_HTTP3
+      quic_sv_ssl_ctx, quic_cert_tree_.get(),
+#endif // ENABLE_HTTP3
+      ticket_keys_, this, config->conn.downstream);
 #ifdef HAVE_MRUBY
   if (single_worker_->create_mruby_context() != 0) {
     return -1;
   }
 #endif // HAVE_MRUBY
+
+#ifdef ENABLE_HTTP3
   if (single_worker_->setup_quic_server_socket() != 0) {
     return -1;
   }
+#endif // ENABLE_HTTP3
 
   return 0;
 }
@@ -288,14 +301,16 @@ int ConnectionHandler::create_worker_thread(size_t num) {
 #  endif // HAVE_NEVERBLEED
   );
 
+#  ifdef ENABLE_HTTP3
   quic_cert_tree_ = tls::create_cert_lookup_tree();
   auto quic_sv_ssl_ctx = tls::setup_quic_server_ssl_context(
       quic_all_ssl_ctx_, quic_indexed_ssl_ctx_, quic_cert_tree_.get()
-#  ifdef HAVE_NEVERBLEED
+#    ifdef HAVE_NEVERBLEED
                                                     ,
       nb_
-#  endif // HAVE_NEVERBLEED
+#    endif // HAVE_NEVERBLEED
   );
+#  endif // ENABLE_HTTP3
 
   auto cl_ssl_ctx = tls::setup_downstream_client_ssl_context(
 #  ifdef HAVE_NEVERBLEED
@@ -305,7 +320,9 @@ int ConnectionHandler::create_worker_thread(size_t num) {
 
   if (cl_ssl_ctx) {
     all_ssl_ctx_.push_back(cl_ssl_ctx);
+#  ifdef ENABLE_HTTP3
     quic_all_ssl_ctx_.push_back(nullptr);
+#  endif // ENABLE_HTTP3
   }
 
   auto config = get_config();
@@ -329,7 +346,9 @@ int ConnectionHandler::create_worker_thread(size_t num) {
           tlsconf.cacert, memcachedconf.cert_file,
           memcachedconf.private_key_file, nullptr);
       all_ssl_ctx_.push_back(session_cache_ssl_ctx);
+#  ifdef ENABLE_HTTP3
       quic_all_ssl_ctx_.push_back(nullptr);
+#  endif // ENABLE_HTTP3
     }
   }
 
@@ -338,17 +357,22 @@ int ConnectionHandler::create_worker_thread(size_t num) {
 
     auto worker = std::make_unique<Worker>(
         loop, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx, cert_tree_.get(),
-        quic_sv_ssl_ctx, quic_cert_tree_.get(), ticket_keys_, this,
-        config->conn.downstream);
+#  ifdef ENABLE_HTTP3
+        quic_sv_ssl_ctx, quic_cert_tree_.get(),
+#  endif // ENABLE_HTTP3
+        ticket_keys_, this, config->conn.downstream);
 #  ifdef HAVE_MRUBY
     if (worker->create_mruby_context() != 0) {
       return -1;
     }
 #  endif // HAVE_MRUBY
+
+#  ifdef ENABLE_HTTP3
     if ((!apiconf.enabled || i != 0) &&
         worker->setup_quic_server_socket() != 0) {
       return -1;
     }
+#  endif // ENABLE_HTTP3
 
     workers_.push_back(std::move(worker));
     worker_loops_.push_back(loop);
@@ -646,7 +670,9 @@ void ConnectionHandler::handle_ocsp_complete() {
   ev_child_stop(loop_, &ocsp_.chldev);
 
   assert(ocsp_.next < all_ssl_ctx_.size());
+#ifdef ENABLE_HTTP3
   assert(all_ssl_ctx_.size() == quic_all_ssl_ctx_.size());
+#endif // ENABLE_HTTP3
 
   auto ssl_ctx = all_ssl_ctx_[ocsp_.next];
   auto tls_ctx_data =
@@ -674,6 +700,7 @@ void ConnectionHandler::handle_ocsp_complete() {
   if (tlsconf.ocsp.no_verify ||
       tls::verify_ocsp_response(ssl_ctx, ocsp_.resp.data(),
                                 ocsp_.resp.size()) == 0) {
+#ifdef ENABLE_HTTP3
     // We have list of SSL_CTX with the same certificate in
     // quic_all_ssl_ctx_ as well.  Some SSL_CTXs are missing there in
     // that case we get nullptr.
@@ -681,21 +708,22 @@ void ConnectionHandler::handle_ocsp_complete() {
     if (quic_ssl_ctx) {
       auto quic_tls_ctx_data = static_cast<tls::TLSContextData *>(
           SSL_CTX_get_app_data(quic_ssl_ctx));
-#ifndef OPENSSL_IS_BORINGSSL
-#  ifdef HAVE_ATOMIC_STD_SHARED_PTR
+#  ifndef OPENSSL_IS_BORINGSSL
+#    ifdef HAVE_ATOMIC_STD_SHARED_PTR
       std::atomic_store_explicit(
           &quic_tls_ctx_data->ocsp_data,
           std::make_shared<std::vector<uint8_t>>(ocsp_.resp),
           std::memory_order_release);
-#  else  // !HAVE_ATOMIC_STD_SHARED_PTR
+#    else  // !HAVE_ATOMIC_STD_SHARED_PTR
       std::lock_guard<std::mutex> g(quic_tls_ctx_data->mu);
       quic_tls_ctx_data->ocsp_data =
           std::make_shared<std::vector<uint8_t>>(ocsp_.resp);
-#  endif // !HAVE_ATOMIC_STD_SHARED_PTR
-#else    // OPENSSL_IS_BORINGSSL
+#    endif // !HAVE_ATOMIC_STD_SHARED_PTR
+#  else    // OPENSSL_IS_BORINGSSL
       SSL_CTX_set_ocsp_response(ssl_ctx, ocsp_.resp.data(), ocsp_.resp.size());
-#endif   // OPENSSL_IS_BORINGSSL
+#  endif   // OPENSSL_IS_BORINGSSL
     }
+#endif // ENABLE_HTTP3
 
 #ifndef OPENSSL_IS_BORINGSSL
 #  ifdef HAVE_ATOMIC_STD_SHARED_PTR
@@ -877,7 +905,9 @@ SSL_CTX *ConnectionHandler::create_tls_ticket_key_memcached_ssl_ctx() {
       nullptr);
 
   all_ssl_ctx_.push_back(ssl_ctx);
+#ifdef ENABLE_HTTP3
   quic_all_ssl_ctx_.push_back(nullptr);
+#endif // ENABLE_HTTP3
 
   return ssl_ctx;
 }
@@ -940,10 +970,12 @@ ConnectionHandler::get_indexed_ssl_ctx(size_t idx) const {
   return indexed_ssl_ctx_[idx];
 }
 
+#ifdef ENABLE_HTTP3
 const std::vector<SSL_CTX *> &
 ConnectionHandler::get_quic_indexed_ssl_ctx(size_t idx) const {
   return quic_indexed_ssl_ctx_[idx];
 }
+#endif // ENABLE_HTTP3
 
 void ConnectionHandler::set_enable_acceptor_on_ocsp_completion(bool f) {
   enable_acceptor_on_ocsp_completion_ = f;
diff --git a/src/shrpx_connection_handler.h b/src/shrpx_connection_handler.h
index eb86b855..3e8a5406 100644
--- a/src/shrpx_connection_handler.h
+++ b/src/shrpx_connection_handler.h
@@ -159,7 +159,9 @@ public:
   SSL_CTX *get_ssl_ctx(size_t idx) const;
 
   const std::vector<SSL_CTX *> &get_indexed_ssl_ctx(size_t idx) const;
+#ifdef ENABLE_HTTP3
   const std::vector<SSL_CTX *> &get_quic_indexed_ssl_ctx(size_t idx) const;
+#endif // ENABLE_HTTP3
 
 #ifdef HAVE_NEVERBLEED
   void set_neverbleed(neverbleed_t *nb);
@@ -188,8 +190,10 @@ private:
   // selection among them are performed by hostname presented by SNI,
   // and signature algorithm presented by client.
   std::vector<std::vector<SSL_CTX *>> indexed_ssl_ctx_;
+#ifdef ENABLE_HTTP3
   std::vector<SSL_CTX *> quic_all_ssl_ctx_;
   std::vector<std::vector<SSL_CTX *>> quic_indexed_ssl_ctx_;
+#endif // ENABLE_HTTP3
   OCSPUpdateContext ocsp_;
   std::mt19937 &gen_;
   // ev_loop for each worker
@@ -206,7 +210,9 @@ private:
   // Otherwise, nullptr and workers_ has instances of Worker instead.
   std::unique_ptr<Worker> single_worker_;
   std::unique_ptr<tls::CertLookupTree> cert_tree_;
+#ifdef ENABLE_HTTP3
   std::unique_ptr<tls::CertLookupTree> quic_cert_tree_;
+#endif // ENABLE_HTTP3
   std::unique_ptr<MemcachedDispatcher> tls_ticket_key_memcached_dispatcher_;
   // Current TLS session ticket keys.  Note that TLS connection does
   // not refer to this field directly.  They use TicketKeys object in
diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index ca07f2f1..7c822ba8 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -165,7 +165,9 @@ Downstream::Downstream(Upstream *upstream, MemchunkPool *mcpool,
   downstream_wtimer_.data = this;
 
   rcbufs_.reserve(32);
+#ifdef ENABLE_HTTP3
   rcbufs3_.reserve(32);
+#endif // ENABLE_HTTP3
 }
 
 Downstream::~Downstream() {
@@ -205,9 +207,11 @@ Downstream::~Downstream() {
   // explicitly.
   dconn_.reset();
 
+#ifdef ENABLE_HTTP3
   for (auto rcbuf : rcbufs3_) {
     nghttp3_rcbuf_decref(rcbuf);
   }
+#endif // ENABLE_HTTP3
 
   for (auto rcbuf : rcbufs_) {
     nghttp2_rcbuf_decref(rcbuf);
@@ -1134,10 +1138,12 @@ void Downstream::add_rcbuf(nghttp2_rcbuf *rcbuf) {
   rcbufs_.push_back(rcbuf);
 }
 
+#ifdef ENABLE_HTTP3
 void Downstream::add_rcbuf(nghttp3_rcbuf *rcbuf) {
   nghttp3_rcbuf_incref(rcbuf);
   rcbufs3_.push_back(rcbuf);
 }
+#endif // ENABLE_HTTP3
 
 void Downstream::set_downstream_addr_group(
     const std::shared_ptr<DownstreamAddrGroup> &group) {
diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index 20ec54c4..2a50a974 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -38,7 +38,9 @@
 
 #include <nghttp2/nghttp2.h>
 
-#include <nghttp3/nghttp3.h>
+#ifdef ENABLE_HTTP3
+#  include <nghttp3/nghttp3.h>
+#endif // ENABLE_HTTP3
 
 #include "llhttp.h"
 
@@ -490,7 +492,9 @@ public:
   BlockAllocator &get_block_allocator();
 
   void add_rcbuf(nghttp2_rcbuf *rcbuf);
+#ifdef ENABLE_HTTP3
   void add_rcbuf(nghttp3_rcbuf *rcbuf);
+#endif // ENABLE_HTTP3
 
   void
   set_downstream_addr_group(const std::shared_ptr<DownstreamAddrGroup> &group);
@@ -533,7 +537,9 @@ private:
   BlockAllocator balloc_;
 
   std::vector<nghttp2_rcbuf *> rcbufs_;
+#ifdef ENABLE_HTTP3
   std::vector<nghttp3_rcbuf *> rcbufs3_;
+#endif // ENABLE_HTTP3
 
   Request req_;
   Response resp_;
diff --git a/src/shrpx_tls.cc b/src/shrpx_tls.cc
index 79104d54..a86dc1a5 100644
--- a/src/shrpx_tls.cc
+++ b/src/shrpx_tls.cc
@@ -51,9 +51,11 @@
 
 #include <nghttp2/nghttp2.h>
 
-#include <ngtcp2/ngtcp2.h>
-#include <ngtcp2/ngtcp2_crypto.h>
-#include <ngtcp2/ngtcp2_crypto_openssl.h>
+#ifdef ENABLE_HTTP3
+#  include <ngtcp2/ngtcp2.h>
+#  include <ngtcp2/ngtcp2_crypto.h>
+#  include <ngtcp2/ngtcp2_crypto_openssl.h>
+#endif // ENABLE_HTTP3
 
 #include "shrpx_log.h"
 #include "shrpx_client_handler.h"
@@ -64,7 +66,9 @@
 #include "shrpx_memcached_request.h"
 #include "shrpx_memcached_dispatcher.h"
 #include "shrpx_connection_handler.h"
-#include "shrpx_http3_upstream.h"
+#ifdef ENABLE_HTTP3
+#  include "shrpx_http3_upstream.h"
+#endif // ENABLE_HTTP3
 #include "util.h"
 #include "tls.h"
 #include "template.h"
@@ -185,8 +189,12 @@ int servername_callback(SSL *ssl, int *al, void *arg) {
 
   auto hostname = StringRef{std::begin(buf), end_buf};
 
+#ifdef ENABLE_HTTP3
   auto cert_tree = SSL_is_quic(ssl) ? worker->get_quic_cert_lookup_tree()
                                     : worker->get_cert_lookup_tree();
+#else  // !ENABLE_HTTP3
+  auto cert_tree = worker->get_cert_lookup_tree();
+#endif // !ENABLE_HTTP3
 
   auto idx = cert_tree->lookup(hostname);
   if (idx == -1) {
@@ -197,9 +205,14 @@ int servername_callback(SSL *ssl, int *al, void *arg) {
 
   auto conn_handler = worker->get_connection_handler();
 
+#ifdef ENABLE_HTTP3
   const auto &ssl_ctx_list = SSL_is_quic(ssl)
                                  ? conn_handler->get_quic_indexed_ssl_ctx(idx)
                                  : conn_handler->get_indexed_ssl_ctx(idx);
+#else  // !ENABLE_HTTP3
+  const auto &ssl_ctx_list = conn_handler->get_indexed_ssl_ctx(idx);
+#endif // !ENABLE_HTTP3
+
   assert(!ssl_ctx_list.empty());
 
 #if !defined(OPENSSL_IS_BORINGSSL) && !LIBRESSL_IN_USE &&                      \
@@ -608,7 +621,8 @@ int alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
 } // namespace
 #endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
 
-#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+#ifdef ENABLE_HTTP3
+#  if OPENSSL_VERSION_NUMBER >= 0x10002000L
 namespace {
 int quic_alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
                               unsigned char *outlen, const unsigned char *in,
@@ -632,7 +646,8 @@ int quic_alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
   return SSL_TLSEXT_ERR_NOACK;
 }
 } // namespace
-#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+#  endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+#endif   // ENABLE_HTTP3
 
 #if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L
 
@@ -1076,6 +1091,7 @@ SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file,
   return ssl_ctx;
 }
 
+#ifdef ENABLE_HTTP3
 namespace {
 int quic_set_encryption_secrets(SSL *ssl, OSSL_ENCRYPTION_LEVEL ossl_level,
                                 const uint8_t *rx_secret,
@@ -1143,10 +1159,10 @@ auto quic_method = SSL_QUIC_METHOD{
 SSL_CTX *create_quic_ssl_context(const char *private_key_file,
                                  const char *cert_file,
                                  const std::vector<uint8_t> &sct_data
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
                                  ,
                                  neverbleed_t *nb
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
 ) {
   auto ssl_ctx = SSL_CTX_new(TLS_server_method());
   if (!ssl_ctx) {
@@ -1159,14 +1175,14 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
       SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION | SSL_OP_SINGLE_ECDH_USE |
       SSL_OP_SINGLE_DH_USE |
       SSL_OP_CIPHER_SERVER_PREFERENCE
-#if OPENSSL_1_1_1_API
+#  if OPENSSL_1_1_1_API
       // The reason for disabling built-in anti-replay in OpenSSL is
       // that it only works if client gets back to the same server.
       // The freshness check described in
       // https://tools.ietf.org/html/rfc8446#section-8.3 is still
       // performed.
       | SSL_OP_NO_ANTI_REPLAY
-#endif // OPENSSL_1_1_1_API
+#  endif // OPENSSL_1_1_1_API
       ;
 
   auto config = mod_config();
@@ -1194,27 +1210,27 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
     DIE();
   }
 
-#if OPENSSL_1_1_1_API
+#  if OPENSSL_1_1_1_API
   if (SSL_CTX_set_ciphersuites(ssl_ctx, tlsconf.tls13_ciphers.c_str()) == 0) {
     LOG(FATAL) << "SSL_CTX_set_ciphersuites " << tlsconf.tls13_ciphers
                << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
     DIE();
   }
-#endif // OPENSSL_1_1_1_API
+#  endif // OPENSSL_1_1_1_API
 
-#ifndef OPENSSL_NO_EC
-#  if !LIBRESSL_LEGACY_API && OPENSSL_VERSION_NUMBER >= 0x10002000L
+#  ifndef OPENSSL_NO_EC
+#    if !LIBRESSL_LEGACY_API && OPENSSL_VERSION_NUMBER >= 0x10002000L
   if (SSL_CTX_set1_curves_list(ssl_ctx, tlsconf.ecdh_curves.c_str()) != 1) {
     LOG(FATAL) << "SSL_CTX_set1_curves_list " << tlsconf.ecdh_curves
                << " failed";
     DIE();
   }
-#    if !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+#      if !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
   // It looks like we need this function call for OpenSSL 1.0.2.  This
   // function was deprecated in OpenSSL 1.1.0 and BoringSSL.
   SSL_CTX_set_ecdh_auto(ssl_ctx, 1);
-#    endif // !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
-#  else    // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+#      endif // !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+#    else    // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
   // Use P-256, which is sufficiently secure at the time of this
   // writing.
   auto ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
@@ -1225,8 +1241,8 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
   }
   SSL_CTX_set_tmp_ecdh(ssl_ctx, ecdh);
   EC_KEY_free(ecdh);
-#  endif   // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
-#endif     // OPENSSL_NO_EC
+#    endif   // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+#  endif     // OPENSSL_NO_EC
 
   if (!tlsconf.dh_param_file.empty()) {
     // Read DH parameters from file
@@ -1269,20 +1285,20 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
     SSL_CTX_set_default_passwd_cb_userdata(ssl_ctx, config);
   }
 
-#ifndef HAVE_NEVERBLEED
+#  ifndef HAVE_NEVERBLEED
   if (SSL_CTX_use_PrivateKey_file(ssl_ctx, private_key_file,
                                   SSL_FILETYPE_PEM) != 1) {
     LOG(FATAL) << "SSL_CTX_use_PrivateKey_file failed: "
                << ERR_error_string(ERR_get_error(), nullptr);
   }
-#else  // HAVE_NEVERBLEED
+#  else  // HAVE_NEVERBLEED
   std::array<char, NEVERBLEED_ERRBUF_SIZE> errbuf;
   if (neverbleed_load_private_key_file(nb, ssl_ctx, private_key_file,
                                        errbuf.data()) != 1) {
     LOG(FATAL) << "neverbleed_load_private_key_file failed: " << errbuf.data();
     DIE();
   }
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
 
   if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_file) != 1) {
     LOG(FATAL) << "SSL_CTX_use_certificate_file failed: "
@@ -1324,27 +1340,27 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
   }
   SSL_CTX_set_tlsext_servername_callback(ssl_ctx, servername_callback);
   SSL_CTX_set_tlsext_ticket_key_cb(ssl_ctx, ticket_key_cb);
-#ifndef OPENSSL_IS_BORINGSSL
+#  ifndef OPENSSL_IS_BORINGSSL
   SSL_CTX_set_tlsext_status_cb(ssl_ctx, ocsp_resp_cb);
-#endif // OPENSSL_IS_BORINGSSL
+#  endif // OPENSSL_IS_BORINGSSL
 
-#ifdef OPENSSL_IS_BORINGSSL
+#  ifdef OPENSSL_IS_BORINGSSL
   SSL_CTX_set_early_data_enabled(ssl_ctx, 1);
-#endif // OPENSSL_IS_BORINGSSL
+#  endif // OPENSSL_IS_BORINGSSL
 
-#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+#  if OPENSSL_VERSION_NUMBER >= 0x10002000L
   // ALPN selection callback
   SSL_CTX_set_alpn_select_cb(ssl_ctx, quic_alpn_select_proto_cb, nullptr);
-#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+#  endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
 
-#if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&               \
-    !defined(OPENSSL_IS_BORINGSSL)
+#  if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&             \
+      !defined(OPENSSL_IS_BORINGSSL)
   // SSL_extension_supported(TLSEXT_TYPE_signed_certificate_timestamp)
   // returns 1, which means OpenSSL internally handles it.  But
   // OpenSSL handles signed_certificate_timestamp extension specially,
   // and it lets custom handler to process the extension.
   if (!sct_data.empty()) {
-#  if OPENSSL_1_1_1_API
+#    if OPENSSL_1_1_1_API
     // It is not entirely clear to me that SSL_EXT_CLIENT_HELLO is
     // required here.  sct_parse_cb is called without
     // SSL_EXT_CLIENT_HELLO being set.  But the passed context value
@@ -1358,7 +1374,7 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
                  << ERR_error_string(ERR_get_error(), nullptr);
       DIE();
     }
-#  else  // !OPENSSL_1_1_1_API
+#    else  // !OPENSSL_1_1_1_API
     if (SSL_CTX_add_server_custom_ext(
             ssl_ctx, TLSEXT_TYPE_signed_certificate_timestamp,
             legacy_sct_add_cb, legacy_sct_free_cb, nullptr, legacy_sct_parse_cb,
@@ -1367,23 +1383,23 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
                  << ERR_error_string(ERR_get_error(), nullptr);
       DIE();
     }
-#  endif // !OPENSSL_1_1_1_API
+#    endif // !OPENSSL_1_1_1_API
   }
-#endif // !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&
-       // !defined(OPENSSL_IS_BORINGSSL)
+#  endif // !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&
+         // !defined(OPENSSL_IS_BORINGSSL)
 
-#if OPENSSL_1_1_1_API
+#  if OPENSSL_1_1_1_API
   if (SSL_CTX_set_max_early_data(ssl_ctx,
                                  std::numeric_limits<uint32_t>::max()) != 1) {
     LOG(FATAL) << "SSL_CTX_set_max_early_data failed: "
                << ERR_error_string(ERR_get_error(), nullptr);
     DIE();
   }
-#endif // OPENSSL_1_1_1_API
+#  endif // OPENSSL_1_1_1_API
 
-#ifndef OPENSSL_NO_PSK
+#  ifndef OPENSSL_NO_PSK
   SSL_CTX_set_psk_server_callback(ssl_ctx, psk_server_cb);
-#endif // !LIBRESSL_NO_PSK
+#  endif // !LIBRESSL_NO_PSK
 
   SSL_CTX_set_quic_method(ssl_ctx, &quic_method);
 
@@ -1395,6 +1411,7 @@ SSL_CTX *create_quic_ssl_context(const char *private_key_file,
 
   return ssl_ctx;
 }
+#endif // ENABLE_HTTP3
 
 namespace {
 int select_h2_next_proto_cb(SSL *ssl, unsigned char **out,
@@ -2101,9 +2118,11 @@ bool in_proto_list(const std::vector<StringRef> &protos,
 }
 
 bool upstream_tls_enabled(const ConnectionConfig &connconf) {
+#ifdef ENABLE_HTTP3
   if (connconf.quic_listener.addrs.size()) {
     return true;
   }
+#endif // ENABLE_HTTP3
 
   const auto &faddrs = connconf.listener.addrs;
   return std::any_of(std::begin(faddrs), std::end(faddrs),
@@ -2184,14 +2203,15 @@ setup_server_ssl_context(std::vector<SSL_CTX *> &all_ssl_ctx,
   return ssl_ctx;
 }
 
+#ifdef ENABLE_HTTP3
 SSL_CTX *setup_quic_server_ssl_context(
     std::vector<SSL_CTX *> &all_ssl_ctx,
     std::vector<std::vector<SSL_CTX *>> &indexed_ssl_ctx,
     CertLookupTree *cert_tree
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
     ,
     neverbleed_t *nb
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
 ) {
   auto config = get_config();
 
@@ -2204,10 +2224,10 @@ SSL_CTX *setup_quic_server_ssl_context(
   auto ssl_ctx =
       create_quic_ssl_context(tlsconf.private_key_file.c_str(),
                               tlsconf.cert_file.c_str(), tlsconf.sct_data
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
                               ,
                               nb
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
       );
 
   all_ssl_ctx.push_back(ssl_ctx);
@@ -2222,10 +2242,10 @@ SSL_CTX *setup_quic_server_ssl_context(
   for (auto &c : tlsconf.subcerts) {
     auto ssl_ctx = create_quic_ssl_context(c.private_key_file.c_str(),
                                            c.cert_file.c_str(), c.sct_data
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
                                            ,
                                            nb
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
     );
     all_ssl_ctx.push_back(ssl_ctx);
 
@@ -2238,6 +2258,7 @@ SSL_CTX *setup_quic_server_ssl_context(
 
   return ssl_ctx;
 }
+#endif // ENABLE_HTTP3
 
 SSL_CTX *setup_downstream_client_ssl_context(
 #ifdef HAVE_NEVERBLEED
diff --git a/src/shrpx_tls.h b/src/shrpx_tls.h
index ebc4aa27..5d751c0f 100644
--- a/src/shrpx_tls.h
+++ b/src/shrpx_tls.h
@@ -100,15 +100,17 @@ SSL_CTX *create_ssl_client_context(
                                 unsigned char *outlen, const unsigned char *in,
                                 unsigned int inlen, void *arg));
 
+#ifdef ENABLE_HTTP3
 SSL_CTX *create_quic_ssl_client_context(
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
     neverbleed_t *nb,
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
     const StringRef &cacert, const StringRef &cert_file,
     const StringRef &private_key_file,
     int (*next_proto_select_cb)(SSL *s, unsigned char **out,
                                 unsigned char *outlen, const unsigned char *in,
                                 unsigned int inlen, void *arg));
+#endif // ENABLE_HTTP3
 
 ClientHandler *accept_connection(Worker *worker, int fd, sockaddr *addr,
                                  int addrlen, const UpstreamAddr *faddr);
@@ -227,15 +229,17 @@ setup_server_ssl_context(std::vector<SSL_CTX *> &all_ssl_ctx,
 #endif // HAVE_NEVERBLEED
 );
 
+#ifdef ENABLE_HTTP3
 SSL_CTX *setup_quic_server_ssl_context(
     std::vector<SSL_CTX *> &all_ssl_ctx,
     std::vector<std::vector<SSL_CTX *>> &indexed_ssl_ctx,
     CertLookupTree *cert_tree
-#ifdef HAVE_NEVERBLEED
+#  ifdef HAVE_NEVERBLEED
     ,
     neverbleed_t *nb
-#endif // HAVE_NEVERBLEED
+#  endif // HAVE_NEVERBLEED
 );
+#endif // ENABLE_HTTP3
 
 // Setups client side SSL_CTX.
 SSL_CTX *setup_downstream_client_ssl_context(
diff --git a/src/shrpx_worker.cc b/src/shrpx_worker.cc
index 0a4ed3c7..b153b0e6 100644
--- a/src/shrpx_worker.cc
+++ b/src/shrpx_worker.cc
@@ -39,8 +39,10 @@
 #ifdef HAVE_MRUBY
 #  include "shrpx_mruby.h"
 #endif // HAVE_MRUBY
-#include "shrpx_quic.h"
-#include "shrpx_quic_listener.h"
+#ifdef ENABLE_HTTP3
+#  include "shrpx_quic.h"
+#  include "shrpx_quic_listener.h"
+#endif // ENABLE_HTTP3
 #include "util.h"
 #include "template.h"
 
@@ -132,23 +134,29 @@ create_downstream_key(const std::shared_ptr<SharedDownstreamAddr> &shared_addr,
 
 Worker::Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
                SSL_CTX *tls_session_cache_memcached_ssl_ctx,
-               tls::CertLookupTree *cert_tree, SSL_CTX *quic_sv_ssl_ctx,
-               tls::CertLookupTree *quic_cert_tree,
+               tls::CertLookupTree *cert_tree,
+#ifdef ENABLE_HTTP3
+               SSL_CTX *quic_sv_ssl_ctx, tls::CertLookupTree *quic_cert_tree,
+#endif // ENABLE_HTTP3
                const std::shared_ptr<TicketKeys> &ticket_keys,
                ConnectionHandler *conn_handler,
                std::shared_ptr<DownstreamConfig> downstreamconf)
     : randgen_(util::make_mt19937()),
       worker_stat_{},
       dns_tracker_(loop),
+#ifdef ENABLE_HTTP3
       quic_upstream_addrs_{get_config()->conn.quic_listener.addrs},
+#endif // ENABLE_HTTP3
       loop_(loop),
       sv_ssl_ctx_(sv_ssl_ctx),
       cl_ssl_ctx_(cl_ssl_ctx),
       cert_tree_(cert_tree),
       conn_handler_(conn_handler),
+#ifdef ENABLE_HTTP3
       quic_sv_ssl_ctx_{quic_sv_ssl_ctx},
       quic_cert_tree_{quic_cert_tree},
       quic_conn_handler_{this},
+#endif // ENABLE_HTTP3
       ticket_keys_(ticket_keys),
       connect_blocker_(
           std::make_unique<ConnectBlocker>(randgen_, loop_, nullptr, nullptr)),
@@ -511,9 +519,11 @@ void Worker::process_events() {
 
 tls::CertLookupTree *Worker::get_cert_lookup_tree() const { return cert_tree_; }
 
+#ifdef ENABLE_HTTP3
 tls::CertLookupTree *Worker::get_quic_cert_lookup_tree() const {
   return quic_cert_tree_;
 }
+#endif // ENABLE_HTTP3
 
 std::shared_ptr<TicketKeys> Worker::get_ticket_keys() {
 #ifdef HAVE_ATOMIC_STD_SHARED_PTR
@@ -545,7 +555,9 @@ SSL_CTX *Worker::get_sv_ssl_ctx() const { return sv_ssl_ctx_; }
 
 SSL_CTX *Worker::get_cl_ssl_ctx() const { return cl_ssl_ctx_; }
 
+#ifdef ENABLE_HTTP3
 SSL_CTX *Worker::get_quic_sv_ssl_ctx() const { return quic_sv_ssl_ctx_; }
+#endif // ENABLE_HTTP3
 
 void Worker::set_graceful_shutdown(bool f) { graceful_shutdown_ = f; }
 
@@ -591,12 +603,15 @@ ConnectionHandler *Worker::get_connection_handler() const {
   return conn_handler_;
 }
 
+#ifdef ENABLE_HTTP3
 QUICConnectionHandler *Worker::get_quic_connection_handler() {
   return &quic_conn_handler_;
 }
+#endif // ENABLE_HTTP3
 
 DNSTracker *Worker::get_dns_tracker() { return &dns_tracker_; }
 
+#ifdef ENABLE_HTTP3
 int Worker::setup_quic_server_socket() {
   for (auto &addr : quic_upstream_addrs_) {
     assert(!addr.host_unix);
@@ -609,6 +624,7 @@ int Worker::setup_quic_server_socket() {
 
   return 0;
 }
+#endif // ENABLE_HTTP3
 
 namespace {
 size_t match_downstream_addr_group_host(
diff --git a/src/shrpx_worker.h b/src/shrpx_worker.h
index 02ece027..e4e83e6e 100644
--- a/src/shrpx_worker.h
+++ b/src/shrpx_worker.h
@@ -50,7 +50,9 @@
 #include "shrpx_live_check.h"
 #include "shrpx_connect_blocker.h"
 #include "shrpx_dns_tracker.h"
-#include "shrpx_quic_connection_handler.h"
+#ifdef ENABLE_HTTP3
+#  include "shrpx_quic_connection_handler.h"
+#endif // ENABLE_HTTP3
 #include "allocator.h"
 
 using namespace nghttp2;
@@ -62,7 +64,9 @@ class ConnectBlocker;
 class MemcachedDispatcher;
 struct UpstreamAddr;
 class ConnectionHandler;
+#ifdef ENABLE_HTTP3
 class QUICListener;
+#endif // ENABLE_HTTP3
 
 #ifdef HAVE_MRUBY
 namespace mruby {
@@ -271,8 +275,10 @@ class Worker {
 public:
   Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
          SSL_CTX *tls_session_cache_memcached_ssl_ctx,
-         tls::CertLookupTree *cert_tree, SSL_CTX *quic_sv_ssl_ctx,
-         tls::CertLookupTree *quic_cert_tree,
+         tls::CertLookupTree *cert_tree,
+#ifdef ENABLE_HTTP3
+         SSL_CTX *quic_sv_ssl_ctx, tls::CertLookupTree *quic_cert_tree,
+#endif // ENABLE_HTTP3
          const std::shared_ptr<TicketKeys> &ticket_keys,
          ConnectionHandler *conn_handler,
          std::shared_ptr<DownstreamConfig> downstreamconf);
@@ -283,7 +289,9 @@ public:
   void send(const WorkerEvent &event);
 
   tls::CertLookupTree *get_cert_lookup_tree() const;
+#ifdef ENABLE_HTTP3
   tls::CertLookupTree *get_quic_cert_lookup_tree() const;
+#endif // ENABLE_HTTP3
 
   // These 2 functions make a lock m_ to get/set ticket keys
   // atomically.
@@ -294,7 +302,9 @@ public:
   struct ev_loop *get_loop() const;
   SSL_CTX *get_sv_ssl_ctx() const;
   SSL_CTX *get_cl_ssl_ctx() const;
+#ifdef ENABLE_HTTP3
   SSL_CTX *get_quic_sv_ssl_ctx() const;
+#endif // ENABLE_HTTP3
 
   void set_graceful_shutdown(bool f);
   bool get_graceful_shutdown() const;
@@ -324,11 +334,13 @@ public:
 
   ConnectionHandler *get_connection_handler() const;
 
+#ifdef ENABLE_HTTP3
   QUICConnectionHandler *get_quic_connection_handler();
 
-  DNSTracker *get_dns_tracker();
-
   int setup_quic_server_socket();
+#endif // ENABLE_HTTP3
+
+  DNSTracker *get_dns_tracker();
 
 private:
 #ifndef NOTHREADS
@@ -344,8 +356,10 @@ private:
   WorkerStat worker_stat_;
   DNSTracker dns_tracker_;
 
+#ifdef ENABLE_HTTP3
   std::vector<UpstreamAddr> quic_upstream_addrs_;
   std::vector<std::unique_ptr<QUICListener>> quic_listeners_;
+#endif // ENABLE_HTTP3
 
   std::shared_ptr<DownstreamConfig> downstreamconf_;
   std::unique_ptr<MemcachedDispatcher> session_cache_memcached_dispatcher_;
@@ -360,10 +374,12 @@ private:
   SSL_CTX *cl_ssl_ctx_;
   tls::CertLookupTree *cert_tree_;
   ConnectionHandler *conn_handler_;
+#ifdef ENABLE_HTTP3
   SSL_CTX *quic_sv_ssl_ctx_;
   tls::CertLookupTree *quic_cert_tree_;
 
   QUICConnectionHandler quic_conn_handler_;
+#endif // ENABLE_HTTP3
 
 #ifndef HAVE_ATOMIC_STD_SHARED_PTR
   std::mutex ticket_keys_m_;