diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index 7b72888e..d74dc907 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -453,7 +453,7 @@ int Http2Handler::fill_wb() {
 
 int Http2Handler::read_clear() {
   int rv;
-  std::array<uint8_t, 8192> buf;
+  std::array<uint8_t, 8_k> buf;
 
   for (;;) {
     ssize_t nread;
@@ -570,7 +570,7 @@ int Http2Handler::tls_handshake() {
 }
 
 int Http2Handler::read_tls() {
-  std::array<uint8_t, 8192> buf;
+  std::array<uint8_t, 8_k> buf;
 
   ERR_clear_error();
 
diff --git a/src/HttpServer.h b/src/HttpServer.h
index 212f12ad..7128ddb2 100644
--- a/src/HttpServer.h
+++ b/src/HttpServer.h
@@ -45,6 +45,7 @@
 
 #include "http2.h"
 #include "buffer.h"
+#include "template.h"
 
 namespace nghttp2 {
 
@@ -155,7 +156,7 @@ public:
 
   struct ev_loop *get_loop() const;
 
-  using WriteBuf = Buffer<65536>;
+  using WriteBuf = Buffer<64_k>;
 
   WriteBuf *get_wb();
 
diff --git a/src/app_helper.cc b/src/app_helper.cc
index 58f8439c..2ce51af7 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -58,6 +58,7 @@
 #include "app_helper.h"
 #include "util.h"
 #include "http2.h"
+#include "template.h"
 
 namespace nghttp2 {
 
@@ -463,7 +464,7 @@ ssize_t deflate_data(uint8_t *out, size_t outlen, const uint8_t *in,
                      size_t inlen) {
   int rv;
   z_stream zst;
-  uint8_t temp_out[8192];
+  uint8_t temp_out[8_k];
   auto temp_outlen = sizeof(temp_out);
 
   zst.next_in = Z_NULL;
diff --git a/src/asio_client_session_impl.cc b/src/asio_client_session_impl.cc
index 9cb57c90..7baa385e 100644
--- a/src/asio_client_session_impl.cc
+++ b/src/asio_client_session_impl.cc
@@ -313,7 +313,7 @@ bool session_impl::setup_session() {
     return false;
   }
 
-  const uint32_t window_size = 256 * 1024 * 1024;
+  const uint32_t window_size = 256_m;
 
   std::array<nghttp2_settings_entry, 2> iv{
       {{NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 100},
diff --git a/src/asio_client_session_impl.h b/src/asio_client_session_impl.h
index 88bbad83..37032d68 100644
--- a/src/asio_client_session_impl.h
+++ b/src/asio_client_session_impl.h
@@ -31,6 +31,8 @@
 
 #include <nghttp2/asio_http2_client.h>
 
+#include "template.h"
+
 namespace nghttp2 {
 namespace asio_http2 {
 namespace client {
@@ -90,8 +92,8 @@ public:
   void do_write();
 
 protected:
-  boost::array<uint8_t, 8192> rb_;
-  boost::array<uint8_t, 65536> wb_;
+  boost::array<uint8_t, 8_k> rb_;
+  boost::array<uint8_t, 64_k> wb_;
   std::size_t wblen_;
 
 private:
diff --git a/src/asio_server_connection.h b/src/asio_server_connection.h
index 5ce48d92..0d58b882 100644
--- a/src/asio_server_connection.h
+++ b/src/asio_server_connection.h
@@ -49,6 +49,7 @@
 #include "asio_server_http2_handler.h"
 #include "asio_server_serve_mux.h"
 #include "util.h"
+#include "template.h"
 
 namespace nghttp2 {
 
@@ -153,9 +154,9 @@ private:
   std::shared_ptr<http2_handler> handler_;
 
   /// Buffer for incoming data.
-  boost::array<uint8_t, 8192> buffer_;
+  boost::array<uint8_t, 8_k> buffer_;
 
-  boost::array<uint8_t, 65536> outbuf_;
+  boost::array<uint8_t, 64_k> outbuf_;
 
   bool writing_;
 };
diff --git a/src/deflatehd.cc b/src/deflatehd.cc
index cd0c5d59..565a4790 100644
--- a/src/deflatehd.cc
+++ b/src/deflatehd.cc
@@ -49,6 +49,10 @@ extern "C" {
 #include "comp_helper.h"
 }
 
+#include "template.h"
+
+namespace nghttp2 {
+
 typedef struct {
   size_t table_size;
   size_t deflate_table_size;
@@ -122,7 +126,7 @@ static void deflate_hd(nghttp2_hd_deflater *deflater,
   ssize_t rv;
   nghttp2_bufs bufs;
 
-  nghttp2_bufs_init2(&bufs, 4096, 16, 0, nghttp2_mem_default());
+  nghttp2_bufs_init2(&bufs, 4_k, 16, 0, nghttp2_mem_default());
 
   rv = nghttp2_hd_deflate_hd_bufs(deflater, &bufs, (nghttp2_nv *)nva.data(),
                                   nva.size());
@@ -448,3 +452,7 @@ int main(int argc, char **argv) {
           output_sum, comp_ratio);
   return 0;
 }
+
+} // namespace nghttp2
+
+int main(int argc, char **argv) { return nghttp2::main(argc, argv); }
diff --git a/src/h2load.cc b/src/h2load.cc
index cb91fbf4..28e138ed 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -506,7 +506,7 @@ int Client::on_write() {
 }
 
 int Client::read_clear() {
-  uint8_t buf[8192];
+  uint8_t buf[8_k];
 
   for (;;) {
     ssize_t nread;
@@ -626,7 +626,7 @@ int Client::tls_handshake() {
 }
 
 int Client::read_tls() {
-  uint8_t buf[8192];
+  uint8_t buf[8_k];
 
   ERR_clear_error();
 
diff --git a/src/h2load.h b/src/h2load.h
index 78a20389..e965cd37 100644
--- a/src/h2load.h
+++ b/src/h2load.h
@@ -50,6 +50,7 @@
 
 #include "http2.h"
 #include "buffer.h"
+#include "template.h"
 
 using namespace nghttp2;
 
@@ -200,7 +201,7 @@ struct Client {
   // The number of requests this client has done so far.
   size_t req_done;
   int fd;
-  Buffer<65536> wb;
+  Buffer<64_k> wb;
 
   enum { ERR_CONNECT_FAIL = -100 };
 
diff --git a/src/memchunk.h b/src/memchunk.h
index 0f12c15e..1673a343 100644
--- a/src/memchunk.h
+++ b/src/memchunk.h
@@ -228,7 +228,7 @@ template <typename Memchunk> struct Memchunks {
   size_t len;
 };
 
-using Memchunk16K = Memchunk<16384>;
+using Memchunk16K = Memchunk<16_k>;
 using MemchunkPool = Pool<Memchunk16K>;
 using DefaultMemchunks = Memchunks<Memchunk16K>;
 
diff --git a/src/nghttp.cc b/src/nghttp.cc
index b1d99408..696b8b51 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -95,7 +95,7 @@ constexpr auto anchors = std::array<Anchor, 5>{{
 } // namespace
 
 Config::Config()
-    : output_upper_thres(1024 * 1024), padding(0),
+    : padding(0),
       peer_max_concurrent_streams(NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS),
       header_table_size(-1), weight(NGHTTP2_DEFAULT_WEIGHT), multiply(1),
       timeout(0.), window_bits(-1), connection_window_bits(-1), verbose(0),
@@ -362,7 +362,7 @@ int submit_request(HttpClient *client, const Headers &headers, Request *req) {
   if (config.continuation) {
     for (size_t i = 0; i < 6; ++i) {
       build_headers.emplace_back("continuation-test-" + util::utos(i + 1),
-                                 std::string(4096, '-'));
+                                 std::string(4_k, '-'));
     }
   }
   auto num_initial_headers = build_headers.size();
@@ -634,7 +634,7 @@ void HttpClient::disconnect() {
 int HttpClient::read_clear() {
   ev_timer_again(loop, &rt);
 
-  std::array<uint8_t, 8192> buf;
+  std::array<uint8_t, 8_k> buf;
 
   for (;;) {
     ssize_t nread;
@@ -1149,7 +1149,7 @@ int HttpClient::read_tls() {
 
   ERR_clear_error();
 
-  std::array<uint8_t, 8192> buf;
+  std::array<uint8_t, 8_k> buf;
   for (;;) {
     auto rv = SSL_read(ssl, buf.data(), buf.size());
 
@@ -1525,7 +1525,7 @@ int on_data_chunk_recv_callback(nghttp2_session *session, uint8_t flags,
 
   if (req->inflater) {
     while (len > 0) {
-      const size_t MAX_OUTLEN = 4096;
+      const size_t MAX_OUTLEN = 4_k;
       std::array<uint8_t, MAX_OUTLEN> out;
       size_t outlen = MAX_OUTLEN;
       size_t tlen = len;
@@ -2244,7 +2244,7 @@ int run(char **uris, int n) {
                     << std::endl;
         }
         while (1) {
-          std::array<char, 1024> buf;
+          std::array<char, 1_k> buf;
           ssize_t rret, wret;
           while ((rret = read(0, buf.data(), buf.size())) == -1 &&
                  errno == EINTR)
diff --git a/src/nghttp.h b/src/nghttp.h
index 0a7ee351..5aaa374c 100644
--- a/src/nghttp.h
+++ b/src/nghttp.h
@@ -52,6 +52,7 @@
 #include "buffer.h"
 #include "http2.h"
 #include "nghttp2_gzip.h"
+#include "template.h"
 
 namespace nghttp2 {
 
@@ -68,7 +69,6 @@ struct Config {
   std::string datafile;
   std::string harfile;
   nghttp2_option *http2_option;
-  size_t output_upper_thres;
   size_t padding;
   ssize_t peer_max_concurrent_streams;
   ssize_t header_table_size;
@@ -260,7 +260,7 @@ struct HttpClient {
   // true if the response message of HTTP Upgrade request is fully
   // received. It is not relevant the upgrade succeeds, or not.
   bool upgrade_response_complete;
-  Buffer<65536> wb;
+  Buffer<64_k> wb;
   // SETTINGS payload sent as token68 in HTTP Upgrade
   std::array<uint8_t, 128> settings_payload;
 
diff --git a/src/shrpx.cc b/src/shrpx.cc
index 1392c450..ab1cb486 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -945,8 +945,8 @@ void fill_default_config() {
   mod_config()->downstream_connections_per_host = 8;
   mod_config()->downstream_connections_per_frontend = 0;
   mod_config()->listener_disable_timeout = 0.;
-  mod_config()->downstream_request_buffer_size = 16 * 1024;
-  mod_config()->downstream_response_buffer_size = 16 * 1024;
+  mod_config()->downstream_request_buffer_size = 16_k;
+  mod_config()->downstream_response_buffer_size = 16_k;
   mod_config()->no_server_push = false;
   mod_config()->host_unix = false;
   mod_config()->http2_downstream_connections_per_worker = 0;
@@ -955,7 +955,7 @@ void fill_default_config() {
   mod_config()->fetch_ocsp_response_file =
       strcopy(PKGDATADIR "/fetch-ocsp-response");
   mod_config()->no_ocsp = false;
-  mod_config()->header_field_buffer = 64 * 1024;
+  mod_config()->header_field_buffer = 64_k;
   mod_config()->max_header_fields = 100;
 }
 } // namespace
diff --git a/src/shrpx_client_handler.h b/src/shrpx_client_handler.h
index 4367c2b5..a2df98eb 100644
--- a/src/shrpx_client_handler.h
+++ b/src/shrpx_client_handler.h
@@ -119,7 +119,7 @@ public:
   Worker *get_worker() const;
 
   using WriteBuf = Buffer<32768>;
-  using ReadBuf = Buffer<8192>;
+  using ReadBuf = Buffer<8_k>;
 
   WriteBuf *get_wb();
   ReadBuf *get_rb();
diff --git a/src/shrpx_connection_handler.cc b/src/shrpx_connection_handler.cc
index 50f3368b..cd93d44d 100644
--- a/src/shrpx_connection_handler.cc
+++ b/src/shrpx_connection_handler.cc
@@ -455,7 +455,7 @@ int ConnectionHandler::start_ocsp_update(const char *cert_file) {
 }
 
 void ConnectionHandler::read_ocsp_chunk() {
-  std::array<uint8_t, 4096> buf;
+  std::array<uint8_t, 4_k> buf;
   for (;;) {
     ssize_t n;
     while ((n = read(ocsp_.fd, buf.data(), buf.size())) == -1 && errno == EINTR)
diff --git a/src/shrpx_http2_session.h b/src/shrpx_http2_session.h
index 2fa2de5a..6f642063 100644
--- a/src/shrpx_http2_session.h
+++ b/src/shrpx_http2_session.h
@@ -177,7 +177,7 @@ public:
     CONNECTION_CHECK_STARTED
   };
 
-  using ReadBuf = Buffer<8192>;
+  using ReadBuf = Buffer<8_k>;
   using WriteBuf = Buffer<32768>;
 
 private:
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index 500286eb..34f06b56 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -729,7 +729,7 @@ int HttpDownstreamConnection::on_read() {
   }
 
   ev_timer_again(conn_.loop, &conn_.rt);
-  std::array<uint8_t, 8192> buf;
+  std::array<uint8_t, 8_k> buf;
   int rv;
 
   if (downstream_->get_upgraded()) {
diff --git a/src/shrpx_log.cc b/src/shrpx_log.cc
index 1446df6e..199114f7 100644
--- a/src/shrpx_log.cc
+++ b/src/shrpx_log.cc
@@ -125,7 +125,7 @@ Log::~Log() {
     return;
   }
 
-  char buf[4096];
+  char buf[4_k];
   auto tty = lgconf->errorlog_tty;
 
   lgconf->update_tstamp(std::chrono::system_clock::now());
@@ -172,7 +172,7 @@ void upstream_accesslog(const std::vector<LogFragment> &lfv,
     return;
   }
 
-  char buf[4096];
+  char buf[4_k];
 
   auto downstream = lgsp.downstream;
 
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 28777e3d..535909e6 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -464,7 +464,7 @@ SpdyUpstream::SpdyUpstream(uint16_t version, ClientHandler *handler)
   rv = spdylay_session_server_new(&session_, version, &callbacks, this);
   assert(rv == 0);
 
-  uint32_t max_buffer = 65536;
+  uint32_t max_buffer = 64_k;
   rv = spdylay_session_set_option(session_,
                                   SPDYLAY_OPT_MAX_RECV_CTRL_FRAME_BUFFER,
                                   &max_buffer, sizeof(max_buffer));
diff --git a/src/template.h b/src/template.h
index 144aed1b..4d7342c3 100644
--- a/src/template.h
+++ b/src/template.h
@@ -145,6 +145,18 @@ template <typename T> void dlist_delete_all(DList<T> &dl) {
   }
 }
 
+constexpr unsigned long long operator"" _k(unsigned long long k) {
+  return k * 1024;
+}
+
+constexpr unsigned long long operator"" _m(unsigned long long m) {
+  return m * 1024 * 1024;
+}
+
+constexpr unsigned long long operator"" _g(unsigned long long g) {
+  return g * 1024 * 1024 * 1024;
+}
+
 } // namespace nghttp2
 
 #endif // TEMPLATE_H