diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index 60a27eb6..95584218 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -402,11 +402,11 @@ int Http2Handler::fill_wb() {
 
 int Http2Handler::read_clear() {
   int rv;
-  uint8_t buf[8192];
+  std::array<uint8_t, 8192> buf;
 
   for (;;) {
     ssize_t nread;
-    while ((nread = read(fd_, buf, sizeof(buf))) == -1 && errno == EINTR)
+    while ((nread = read(fd_, buf.data(), buf.size())) == -1 && errno == EINTR)
       ;
     if (nread == -1) {
       if (errno == EAGAIN || errno == EWOULDBLOCK) {
@@ -417,7 +417,7 @@ int Http2Handler::read_clear() {
     if (nread == 0) {
       return -1;
     }
-    rv = nghttp2_session_mem_recv(session_, buf, nread);
+    rv = nghttp2_session_mem_recv(session_, buf.data(), nread);
     if (rv < 0) {
       if (rv != NGHTTP2_ERR_BAD_PREFACE) {
         std::cerr << "nghttp2_session_mem_recv() returned error: "
@@ -516,12 +516,12 @@ int Http2Handler::tls_handshake() {
 }
 
 int Http2Handler::read_tls() {
-  uint8_t buf[8192];
+  std::array<uint8_t, 8192> buf;
 
   ERR_clear_error();
 
   for (;;) {
-    auto rv = SSL_read(ssl_, buf, sizeof(buf));
+    auto rv = SSL_read(ssl_, buf.data(), buf.size());
 
     if (rv == 0) {
       return -1;
@@ -541,7 +541,7 @@ int Http2Handler::read_tls() {
     }
 
     auto nread = rv;
-    rv = nghttp2_session_mem_recv(session_, buf, nread);
+    rv = nghttp2_session_mem_recv(session_, buf.data(), nread);
     if (rv < 0) {
       if (rv != NGHTTP2_ERR_BAD_PREFACE) {
         std::cerr << "nghttp2_session_mem_recv() returned error: "
@@ -624,7 +624,7 @@ int Http2Handler::on_connect() {
   if (r != 0) {
     return r;
   }
-  nghttp2_settings_entry entry[4];
+  std::array<nghttp2_settings_entry, 4> entry;
   size_t niv = 1;
 
   entry[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
@@ -635,7 +635,7 @@ int Http2Handler::on_connect() {
     entry[niv].value = sessions_->get_config()->header_table_size;
     ++niv;
   }
-  r = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry, niv);
+  r = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry.data(), niv);
   if (r != 0) {
     return r;
   }
@@ -682,20 +682,18 @@ int Http2Handler::submit_file_response(const std::string &status,
                                        nghttp2_data_provider *data_prd) {
   std::string content_length = util::utos(file_length);
   std::string last_modified_str;
-  nghttp2_nv nva[] = {
-      http2::make_nv_ls(":status", status),
-      http2::make_nv_ls("server", NGHTTPD_SERVER),
-      http2::make_nv_ls("content-length", content_length),
-      http2::make_nv_ll("cache-control", "max-age=3600"),
-      http2::make_nv_ls("date", sessions_->get_cached_date()),
-      http2::make_nv_ll("", ""),
-  };
+  auto nva = make_array(http2::make_nv_ls(":status", status),
+                        http2::make_nv_ls("server", NGHTTPD_SERVER),
+                        http2::make_nv_ls("content-length", content_length),
+                        http2::make_nv_ll("cache-control", "max-age=3600"),
+                        http2::make_nv_ls("date", sessions_->get_cached_date()),
+                        http2::make_nv_ll("", ""));
   size_t nvlen = 5;
   if (last_modified != 0) {
     last_modified_str = util::http_date(last_modified);
     nva[nvlen++] = http2::make_nv_ls("last-modified", last_modified_str);
   }
-  return nghttp2_submit_response(session_, stream->stream_id, nva, nvlen,
+  return nghttp2_submit_response(session_, stream->stream_id, nva.data(), nvlen,
                                  data_prd);
 }
 
diff --git a/src/nghttp.cc b/src/nghttp.cc
index 9a3f8061..6bed5e9d 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -113,13 +113,13 @@ namespace {
 // Returns numeric address string of |addr|.  If getnameinfo() is
 // failed, "unknown" is returned.
 std::string numeric_name(addrinfo *addr) {
-  char host[NI_MAXHOST];
-  auto rv = getnameinfo(addr->ai_addr, addr->ai_addrlen, host, sizeof(host),
-                        nullptr, 0, NI_NUMERICHOST);
+  std::array<char, NI_MAXHOST> host;
+  auto rv = getnameinfo(addr->ai_addr, addr->ai_addrlen, host.data(),
+                        host.size(), nullptr, 0, NI_NUMERICHOST);
   if (rv != 0) {
     return "unknown";
   }
-  return host;
+  return host.data();
 }
 } // namespace
 
@@ -622,11 +622,11 @@ void HttpClient::disconnect() {
 int HttpClient::read_clear() {
   ev_timer_again(loop, &rt);
 
-  uint8_t buf[8192];
+  std::array<uint8_t, 8192> buf;
 
   for (;;) {
     ssize_t nread;
-    while ((nread = read(fd, buf, sizeof(buf))) == -1 && errno == EINTR)
+    while ((nread = read(fd, buf.data(), buf.size())) == -1 && errno == EINTR)
       ;
     if (nread == -1) {
       if (errno == EAGAIN || errno == EWOULDBLOCK) {
@@ -639,7 +639,7 @@ int HttpClient::read_clear() {
       return -1;
     }
 
-    if (on_readfn(*this, buf, nread) != 0) {
+    if (on_readfn(*this, buf.data(), nread) != 0) {
       return -1;
     }
   }
@@ -773,17 +773,18 @@ int HttpClient::on_upgrade_connect() {
   ssize_t rv;
   record_handshake_time();
   assert(!reqvec.empty());
-  nghttp2_settings_entry iv[32];
-  size_t niv = populate_settings(iv);
-  assert(sizeof(settings_payload) >= 8 * niv);
-  rv = nghttp2_pack_settings_payload(settings_payload, sizeof(settings_payload),
-                                     iv, niv);
+  std::array<nghttp2_settings_entry, 32> iv;
+  size_t niv = populate_settings(iv.data());
+  assert(settings_payload.size() >= 8 * niv);
+  rv = nghttp2_pack_settings_payload(settings_payload.data(),
+                                     settings_payload.size(), iv.data(), niv);
   if (rv < 0) {
     return -1;
   }
   settings_payloadlen = rv;
-  auto token68 = base64::encode(&settings_payload[0],
-                                &settings_payload[settings_payloadlen]);
+  auto token68 =
+      base64::encode(std::begin(settings_payload),
+                     std::begin(settings_payload) + settings_payloadlen);
   util::to_token68(token68);
   std::string req;
   if (reqvec[0]->data_prd) {
@@ -934,8 +935,8 @@ int HttpClient::on_connect() {
     if (!reqvec[0]->data_prd) {
       stream_user_data = reqvec[0].get();
     }
-    rv = nghttp2_session_upgrade(session, settings_payload, settings_payloadlen,
-                                 stream_user_data);
+    rv = nghttp2_session_upgrade(session, settings_payload.data(),
+                                 settings_payloadlen, stream_user_data);
     if (rv != 0) {
       std::cerr << "[ERROR] nghttp2_session_upgrade() returned error: "
                 << nghttp2_strerror(rv) << std::endl;
@@ -953,9 +954,9 @@ int HttpClient::on_connect() {
   // HTTP2-Settings header field has already been submitted to
   // session object.
   if (!need_upgrade()) {
-    nghttp2_settings_entry iv[16];
-    auto niv = populate_settings(iv);
-    rv = nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv, niv);
+    std::array<nghttp2_settings_entry, 16> iv;
+    auto niv = populate_settings(iv.data());
+    rv = nghttp2_submit_settings(session, NGHTTP2_FLAG_NONE, iv.data(), niv);
     if (rv != 0) {
       return -1;
     }
@@ -1112,9 +1113,9 @@ int HttpClient::read_tls() {
 
   ERR_clear_error();
 
-  uint8_t buf[8192];
+  std::array<uint8_t, 8192> buf;
   for (;;) {
-    auto rv = SSL_read(ssl, buf, sizeof(buf));
+    auto rv = SSL_read(ssl, buf.data(), buf.size());
 
     if (rv == 0) {
       return -1;
@@ -1133,7 +1134,7 @@ int HttpClient::read_tls() {
       }
     }
 
-    if (on_readfn(*this, buf, rv) != 0) {
+    if (on_readfn(*this, buf.data(), rv) != 0) {
       return -1;
     }
   }
@@ -1523,10 +1524,11 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
   if (req->inflater) {
     while (len > 0) {
       const size_t MAX_OUTLEN = 4096;
-      uint8_t out[MAX_OUTLEN];
+      std::array<uint8_t, MAX_OUTLEN> out;
       size_t outlen = MAX_OUTLEN;
       size_t tlen = len;
-      int rv = nghttp2_gzip_inflate(req->inflater, out, &outlen, data, &tlen);
+      int rv =
+          nghttp2_gzip_inflate(req->inflater, out.data(), &outlen, data, &tlen);
       if (rv != 0) {
         nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE, stream_id,
                                   NGHTTP2_INTERNAL_ERROR);
@@ -1536,10 +1538,10 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
       req->response_len += outlen;
 
       if (!config.null_out) {
-        std::cout.write(reinterpret_cast<const char *>(out), outlen);
+        std::cout.write(reinterpret_cast<const char *>(out.data()), outlen);
       }
 
-      update_html_parser(client, req, out, outlen, 0);
+      update_html_parser(client, req, out.data(), outlen, 0);
       data += tlen;
       len -= tlen;
     }
@@ -2197,9 +2199,10 @@ int run(char **uris, int n) {
                     << std::endl;
         }
         while (1) {
-          char buf[1024];
+          std::array<char, 1024> buf;
           ssize_t rret, wret;
-          while ((rret = read(0, buf, sizeof(buf))) == -1 && errno == EINTR)
+          while ((rret = read(0, buf.data(), buf.size())) == -1 &&
+                 errno == EINTR)
             ;
           if (rret == 0)
             break;
@@ -2208,7 +2211,8 @@ int run(char **uris, int n) {
                       << std::endl;
             return 1;
           }
-          while ((wret = write(data_fd, buf, rret)) == -1 && errno == EINTR)
+          while ((wret = write(data_fd, buf.data(), rret)) == -1 &&
+                 errno == EINTR)
             ;
           if (wret != rret) {
             std::cerr << "[ERROR] I/O error while writing to temporary file"
diff --git a/src/nghttp.h b/src/nghttp.h
index af3516da..2ee7ffbc 100644
--- a/src/nghttp.h
+++ b/src/nghttp.h
@@ -263,7 +263,7 @@ struct HttpClient {
   bool upgrade_response_complete;
   RingBuf<65536> wb;
   // SETTINGS payload sent as token68 in HTTP Upgrade
-  uint8_t settings_payload[128];
+  std::array<uint8_t, 128> settings_payload;
 
   enum { ERR_CONNECT_FAIL = -100 };
 };
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index 7c1b9660..7456819b 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -1212,7 +1212,7 @@ int Http2Session::on_connect() {
 
   flow_control_ = true;
 
-  nghttp2_settings_entry entry[3];
+  std::array<nghttp2_settings_entry, 3> entry;
   entry[0].settings_id = NGHTTP2_SETTINGS_ENABLE_PUSH;
   entry[0].value = 0;
   entry[1].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
@@ -1221,8 +1221,8 @@ int Http2Session::on_connect() {
   entry[2].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   entry[2].value = (1 << get_config()->http2_downstream_window_bits) - 1;
 
-  rv = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry,
-                               util::array_size(entry));
+  rv = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry.data(),
+                               entry.size());
   if (rv != 0) {
     return -1;
   }
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index a7ee2564..b5f38d71 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -703,15 +703,15 @@ Http2Upstream::Http2Upstream(ClientHandler *handler)
   flow_control_ = true;
 
   // TODO Maybe call from outside?
-  nghttp2_settings_entry entry[2];
+  std::array<nghttp2_settings_entry, 2> entry;
   entry[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
   entry[0].value = get_config()->http2_max_concurrent_streams;
 
   entry[1].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   entry[1].value = (1 << get_config()->http2_upstream_window_bits) - 1;
 
-  rv = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry,
-                               util::array_size(entry));
+  rv = nghttp2_submit_settings(session_, NGHTTP2_FLAG_NONE, entry.data(),
+                               entry.size());
   if (rv != 0) {
     ULOG(ERROR, this) << "nghttp2_submit_settings() returned error: "
                       << nghttp2_strerror(rv);
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index 0e6a6d2b..61873cad 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -637,13 +637,13 @@ http_parser_settings htp_hooks = {
 
 int HttpDownstreamConnection::on_read() {
   ev_timer_again(conn_.loop, &conn_.rt);
-  uint8_t buf[8192];
+  std::array<uint8_t, 8192> buf;
   int rv;
 
   if (downstream_->get_upgraded()) {
     // For upgraded connection, just pass data to the upstream.
     for (;;) {
-      auto nread = conn_.read_clear(buf, sizeof(buf));
+      auto nread = conn_.read_clear(buf.data(), buf.size());
 
       if (nread == 0) {
         return 0;
@@ -653,8 +653,8 @@ int HttpDownstreamConnection::on_read() {
         return nread;
       }
 
-      rv = downstream_->get_upstream()->on_downstream_body(downstream_, buf,
-                                                           nread, true);
+      rv = downstream_->get_upstream()->on_downstream_body(
+          downstream_, buf.data(), nread, true);
       if (rv != 0) {
         return rv;
       }
@@ -667,7 +667,7 @@ int HttpDownstreamConnection::on_read() {
   }
 
   for (;;) {
-    auto nread = conn_.read_clear(buf, sizeof(buf));
+    auto nread = conn_.read_clear(buf.data(), buf.size());
 
     if (nread == 0) {
       return 0;
@@ -677,8 +677,9 @@ int HttpDownstreamConnection::on_read() {
       return nread;
     }
 
-    auto nproc = http_parser_execute(&response_htp_, &htp_hooks,
-                                     reinterpret_cast<char *>(buf), nread);
+    auto nproc =
+        http_parser_execute(&response_htp_, &htp_hooks,
+                            reinterpret_cast<char *>(buf.data()), nread);
 
     if (nproc != static_cast<size_t>(nread)) {
       if (LOG_ENABLED(INFO)) {
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 8e9d5475..ede2625b 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -438,7 +438,7 @@ SpdyUpstream::SpdyUpstream(uint16_t version, ClientHandler *handler)
     initial_window_size_ = 0;
   }
   // TODO Maybe call from outside?
-  spdylay_settings_entry entry[2];
+  std::array<spdylay_settings_entry, 2> entry;
   entry[0].settings_id = SPDYLAY_SETTINGS_MAX_CONCURRENT_STREAMS;
   entry[0].value = get_config()->http2_max_concurrent_streams;
   entry[0].flags = SPDYLAY_ID_FLAG_SETTINGS_NONE;
@@ -447,8 +447,8 @@ SpdyUpstream::SpdyUpstream(uint16_t version, ClientHandler *handler)
   entry[1].value = initial_window_size_;
   entry[1].flags = SPDYLAY_ID_FLAG_SETTINGS_NONE;
 
-  rv = spdylay_submit_settings(session_, SPDYLAY_FLAG_SETTINGS_NONE, entry,
-                               util::array_size(entry));
+  rv = spdylay_submit_settings(session_, SPDYLAY_FLAG_SETTINGS_NONE,
+                               entry.data(), entry.size());
   assert(rv == 0);
 
   if (version >= SPDYLAY_PROTO_SPDY3_1 &&