diff --git a/doc/programmers-guide.rst b/doc/programmers-guide.rst
index c67c09a3..94c72e98 100644
--- a/doc/programmers-guide.rst
+++ b/doc/programmers-guide.rst
@@ -20,17 +20,15 @@ nghttp2 callback functions directly or indirectly. It will lead to the
 crash.  You can submit requests or frames in the callbacks then call
 these functions outside the callbacks.
 
-Currently, `nghttp2_session_send()` and `nghttp2_session_mem_send()`
-do not send client connection preface
-(:macro:`NGHTTP2_CLIENT_CONNECTION_PREFACE`).  The applications are
-responsible to send it before sending any HTTP/2 frames using these
-functions if :type:`nghttp2_session` is configured as client.
-Similarly, `nghttp2_session_recv()` and `nghttp2_session_mem_recv()`
-do not consume client connection preface unless
-`nghttp2_option_set_recv_client_preface()` is used with nonzero option
-value.  The applications are responsible to receive it before calling
-these functions if :type:`nghttp2_session` is configured as server and
-`nghttp2_option_set_recv_client_preface()` is not used.
+`nghttp2_session_send()` and `nghttp2_session_mem_send()` send first
+24 bytes of client magic string (MAGIC)
+(:macro:`NGHTTP2_CLIENT_MAGIC`) on client configuration.  The
+applications are responsible to send SETTINGS frame as part of
+connection preface using `nghttp2_submit_settings()`.  Similarly,
+`nghttp2_session_recv()` and `nghttp2_session_mem_recv()` consume
+MAGIC on server configuration unless
+`nghttp2_option_set_no_recv_client_magic()` is used with nonzero
+option value.
 
 .. _http-messaging:
 
diff --git a/doc/sources/tutorial-client.rst b/doc/sources/tutorial-client.rst
index 0d168991..ceaa14c8 100644
--- a/doc/sources/tutorial-client.rst
+++ b/doc/sources/tutorial-client.rst
@@ -184,9 +184,9 @@ its bufferevent, so it closes underlying connection as well. It also
 calls `nghttp2_session_del()` to delete nghttp2 session object.
 
 We begin HTTP/2 communication by sending client connection preface,
-which is 24 bytes magic byte sequence
-(:macro:`NGHTTP2_CLIENT_CONNECTION_PREFACE`) and SETTINGS frame.  The
-transmission of client connection header is done in
+which is 24 bytes magic byte string (:macro:`NGHTTP2_CLIENT_MAGIC`)
+followed by SETTINGS frame.  First 24 bytes magic string is
+automatically sent by nghttp2 library.  We send SETTINGS frame in
 ``send_client_connection_header()``::
 
     static void send_client_connection_header(http2_session_data *session_data) {
@@ -194,8 +194,7 @@ transmission of client connection header is done in
           {NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 100}};
       int rv;
 
-      bufferevent_write(session_data->bev, NGHTTP2_CLIENT_CONNECTION_PREFACE,
-                        NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
+      /* client 24 bytes magic string will be sent by nghttp2 library */
       rv = nghttp2_submit_settings(session_data->session, NGHTTP2_FLAG_NONE, iv,
                                    ARRLEN(iv));
       if (rv != 0) {
diff --git a/doc/sources/tutorial-server.rst b/doc/sources/tutorial-server.rst
index 12347ef6..8f5b5833 100644
--- a/doc/sources/tutorial-server.rst
+++ b/doc/sources/tutorial-server.rst
@@ -194,15 +194,8 @@ We initialize a nghttp2 session object which is done in
 ``initialize_nghttp2_session()``::
 
     static void initialize_nghttp2_session(http2_session_data *session_data) {
-      nghttp2_option *option;
       nghttp2_session_callbacks *callbacks;
 
-      nghttp2_option_new(&option);
-
-      /* Tells nghttp2_session object that it handles client connection
-         preface */
-      nghttp2_option_set_recv_client_preface(option, 1);
-
       nghttp2_session_callbacks_new(&callbacks);
 
       nghttp2_session_callbacks_set_send_callback(callbacks, send_callback);
@@ -219,20 +212,15 @@ We initialize a nghttp2 session object which is done in
       nghttp2_session_callbacks_set_on_begin_headers_callback(
           callbacks, on_begin_headers_callback);
 
-      nghttp2_session_server_new2(&session_data->session, callbacks, session_data,
-                                  option);
+      nghttp2_session_server_new(&session_data->session, callbacks, session_data);
 
       nghttp2_session_callbacks_del(callbacks);
-      nghttp2_option_del(option);
     }
 
 Since we are creating a server and uses options, the nghttp2 session
 object is created using `nghttp2_session_server_new2()` function.  We
 registers five callbacks for nghttp2 session object.  We'll talk about
-these callbacks later.  Our server only speaks HTTP/2.  In this case,
-we use `nghttp2_option_set_recv_client_preface()` to make
-:type:`nghttp2_session` object handle client connection preface, which
-saves some lines of application code.
+these callbacks later.
 
 After initialization of the nghttp2 session object, we are going to send
 a server connection header in ``send_server_connection_header()``::
diff --git a/examples/client.c b/examples/client.c
index 314efb34..b202df18 100644
--- a/examples/client.c
+++ b/examples/client.c
@@ -528,14 +528,6 @@ static void fetch_uri(const struct URI *uri) {
   connection.ssl = ssl;
   connection.want_io = IO_NONE;
 
-  /* Send connection header in blocking I/O mode */
-  rv = SSL_write(ssl, NGHTTP2_CLIENT_CONNECTION_PREFACE,
-                 NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
-  if (rv <= 0) {
-    dief("SSL_write failed: could not send connection preface",
-         ERR_error_string(ERR_get_error(), NULL));
-  }
-
   /* Here make file descriptor non-block */
   make_non_block(fd);
   set_tcp_nodelay(fd);
diff --git a/examples/libevent-client.c b/examples/libevent-client.c
index 98c194a6..c970629b 100644
--- a/examples/libevent-client.c
+++ b/examples/libevent-client.c
@@ -345,8 +345,7 @@ static void send_client_connection_header(http2_session_data *session_data) {
       {NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 100}};
   int rv;
 
-  bufferevent_write(session_data->bev, NGHTTP2_CLIENT_CONNECTION_PREFACE,
-                    NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
+  /* client 24 bytes magic string will be sent by nghttp2 library */
   rv = nghttp2_submit_settings(session_data->session, NGHTTP2_FLAG_NONE, iv,
                                ARRLEN(iv));
   if (rv != 0) {
diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index e80049b7..969726f4 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -194,32 +194,17 @@ typedef struct {
 /**
  * @macro
  *
- * The client connection preface.
+ * The client magic string, which is the first 24 bytes byte string of
+ * client connection preface.
  */
-#define NGHTTP2_CLIENT_CONNECTION_PREFACE "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
+#define NGHTTP2_CLIENT_MAGIC "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
 
 /**
  * @macro
  *
- * The length of :macro:`NGHTTP2_CLIENT_CONNECTION_PREFACE`.
+ * The length of :macro:`NGHTTP2_CLIENT_MAGIC`.
  */
-#define NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN 24
-
-/**
- * @macro
- *
- * The client connection header.  This macro is obsoleted by
- * NGHTTP2_CLIENT_CONNECTION_PREFACE.
- */
-#define NGHTTP2_CLIENT_CONNECTION_HEADER NGHTTP2_CLIENT_CONNECTION_PREFACE
-
-/**
- * @macro
- *
- * The length of :macro:`NGHTTP2_CLIENT_CONNECTION_HEADER`.
- */
-#define NGHTTP2_CLIENT_CONNECTION_HEADER_LEN                                   \
-  NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN
+#define NGHTTP2_CLIENT_MAGIC_LEN 24
 
 /**
  * @enum
@@ -397,10 +382,10 @@ typedef enum {
    */
   NGHTTP2_ERR_CALLBACK_FAILURE = -902,
   /**
-   * Invalid connection preface was received and further processing is
-   * not possible.
+   * Invalid client magic (see :macro:`NGHTTP2_CLIENT_MAGIC`) was
+   * received and further processing is not possible.
    */
-  NGHTTP2_ERR_BAD_PREFACE = -903
+  NGHTTP2_ERR_BAD_CLIENT_MAGIC = -903
 } nghttp2_error;
 
 /**
@@ -1975,25 +1960,22 @@ nghttp2_option_set_peer_max_concurrent_streams(nghttp2_option *option,
  * @function
  *
  * By default, nghttp2 library, if configured as server, requires
- * first 24 bytes of client connection preface.  In most cases, this
- * will simplify the implementation of server.  But sometimes erver
- * may want to detect the application protocol based on first few
- * bytes on clear text communication.
+ * first 24 bytes of client magic byte string (MAGIC).  In most cases,
+ * this will simplify the implementation of server.  But sometimes
+ * server may want to detect the application protocol based on first
+ * few bytes on clear text communication.
  *
  * If this option is used with nonzero |val|, nghttp2 library does not
- * handle first 24 bytes client connection preface.  It still checks
- * following SETTINGS frame.  This means that applications should deal
- * with 24 bytes connection preface by themselves.
+ * handle MAGIC.  It still checks following SETTINGS frame.  This
+ * means that applications should deal with MAGIC by themselves.
  *
- * If this option is not used or used with zero value, if client
- * connection preface does not match the one
- * (:macro:`NGHTTP2_CLIENT_CONNECTION_PREFACE`) in the HTTP/2
- * specification, `nghttp2_session_recv()` and
- * `nghttp2_session_mem_recv()` will return error
- * :enum:`NGHTTP2_ERR_BAD_PREFACE`, which is fatal error.
+ * If this option is not used or used with zero value, if MAGIC does
+ * not match :macro:`NGHTTP2_CLIENT_MAGIC`, `nghttp2_session_recv()`
+ * and `nghttp2_session_mem_recv()` will return error
+ * :enum:`NGHTTP2_ERR_BAD_CLIENT_MAGIC`, which is fatal error.
  */
 NGHTTP2_EXTERN void
-nghttp2_option_set_no_recv_client_preface(nghttp2_option *option, int val);
+nghttp2_option_set_no_recv_client_magic(nghttp2_option *option, int val);
 
 /**
  * @function
@@ -2310,10 +2292,10 @@ NGHTTP2_EXTERN ssize_t nghttp2_session_mem_send(nghttp2_session *session,
  *     Out of memory.
  * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`
  *     The callback function failed.
- * :enum:`NGHTTP2_ERR_BAD_PREFACE`
- *     Invalid client preface was detected.  This error only returns
+ * :enum:`NGHTTP2_ERR_BAD_CLIENT_MAGIC`
+ *     Invalid client magic was detected.  This error only returns
  *     when |session| was configured as server and
- *     `nghttp2_option_set_no_recv_client_preface()` is not used with
+ *     `nghttp2_option_set_no_recv_client_magic()` is not used with
  *     nonzero value.
  */
 NGHTTP2_EXTERN int nghttp2_session_recv(nghttp2_session *session);
@@ -2346,10 +2328,10 @@ NGHTTP2_EXTERN int nghttp2_session_recv(nghttp2_session *session);
  *     Out of memory.
  * :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`
  *     The callback function failed.
- * :enum:`NGHTTP2_ERR_BAD_PREFACE`
- *     Invalid client preface was detected.  This error only returns
+ * :enum:`NGHTTP2_ERR_BAD_CLIENT_MAGIC`
+ *     Invalid client magic was detected.  This error only returns
  *     when |session| was configured as server and
- *     `nghttp2_option_set_no_recv_client_preface()` is not used with
+ *     `nghttp2_option_set_no_recv_client_magic()` is not used with
  *     nonzero value.
  */
 NGHTTP2_EXTERN ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c
index 5883f72c..15f329cc 100644
--- a/lib/nghttp2_helper.c
+++ b/lib/nghttp2_helper.c
@@ -307,8 +307,8 @@ const char *nghttp2_strerror(int error_code) {
     return "Out of memory";
   case NGHTTP2_ERR_CALLBACK_FAILURE:
     return "The user callback function failed";
-  case NGHTTP2_ERR_BAD_PREFACE:
-    return "Received bad connection preface";
+  case NGHTTP2_ERR_BAD_CLIENT_MAGIC:
+    return "Received bad clinet magic byte string";
   default:
     return "Unknown error code";
   }
diff --git a/lib/nghttp2_option.c b/lib/nghttp2_option.c
index cf9bae02..a45b5e0e 100644
--- a/lib/nghttp2_option.c
+++ b/lib/nghttp2_option.c
@@ -47,10 +47,9 @@ void nghttp2_option_set_peer_max_concurrent_streams(nghttp2_option *option,
   option->peer_max_concurrent_streams = val;
 }
 
-void nghttp2_option_set_no_recv_client_preface(nghttp2_option *option,
-                                               int val) {
-  option->opt_set_mask |= NGHTTP2_OPT_NO_RECV_CLIENT_PREFACE;
-  option->no_recv_client_preface = val;
+void nghttp2_option_set_no_recv_client_magic(nghttp2_option *option, int val) {
+  option->opt_set_mask |= NGHTTP2_OPT_NO_RECV_CLIENT_MAGIC;
+  option->no_recv_client_magic = val;
 }
 
 void nghttp2_option_set_no_http_messaging(nghttp2_option *option, int val) {
diff --git a/lib/nghttp2_option.h b/lib/nghttp2_option.h
index f35339ab..2e56ff07 100644
--- a/lib/nghttp2_option.h
+++ b/lib/nghttp2_option.h
@@ -57,7 +57,7 @@ typedef enum {
    * SETTINGS_MAX_CONCURRENT_STREAMS from the remote endpoint.
    */
   NGHTTP2_OPT_PEER_MAX_CONCURRENT_STREAMS = 1 << 1,
-  NGHTTP2_OPT_NO_RECV_CLIENT_PREFACE = 1 << 2,
+  NGHTTP2_OPT_NO_RECV_CLIENT_MAGIC = 1 << 2,
   NGHTTP2_OPT_NO_HTTP_MESSAGING = 1 << 3,
 } nghttp2_option_flag;
 
@@ -79,9 +79,9 @@ struct nghttp2_option {
    */
   uint8_t no_auto_window_update;
   /**
-   * NGHTTP2_OPT_NO_RECV_CLIENT_PREFACE
+   * NGHTTP2_OPT_NO_RECV_CLIENT_MAGIC
    */
-  uint8_t no_recv_client_preface;
+  uint8_t no_recv_client_magic;
   /**
    * NGHTTP2_OPT_NO_HTTP_MESSAGING
    */
diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index bbb9aaa3..15d0f02c 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -314,9 +314,9 @@ static void active_outbound_item_reset(nghttp2_active_outbound_item *aob,
   aob->state = NGHTTP2_OB_POP_ITEM;
 }
 
-/* This global variable exists for tests where we want to disable this
-   check. */
-int nghttp2_enable_strict_connection_preface_check = 1;
+/* The global variable for tests where we want to disable strict
+   preface handling. */
+int nghttp2_enable_strict_preface = 1;
 
 static int session_new(nghttp2_session **session_ptr,
                        const nghttp2_session_callbacks *callbacks,
@@ -417,10 +417,10 @@ static int session_new(nghttp2_session **session_ptr,
           option->peer_max_concurrent_streams;
     }
 
-    if ((option->opt_set_mask & NGHTTP2_OPT_NO_RECV_CLIENT_PREFACE) &&
-        option->no_recv_client_preface) {
+    if ((option->opt_set_mask & NGHTTP2_OPT_NO_RECV_CLIENT_MAGIC) &&
+        option->no_recv_client_magic) {
 
-      (*session_ptr)->opt_flags |= NGHTTP2_OPTMASK_NO_RECV_CLIENT_PREFACE;
+      (*session_ptr)->opt_flags |= NGHTTP2_OPTMASK_NO_RECV_CLIENT_MAGIC;
     }
 
     if ((option->opt_set_mask & NGHTTP2_OPT_NO_HTTP_MESSAGING) &&
@@ -435,17 +435,23 @@ static int session_new(nghttp2_session **session_ptr,
 
   session_inbound_frame_reset(*session_ptr);
 
-  if (nghttp2_enable_strict_connection_preface_check) {
+  if (nghttp2_enable_strict_preface) {
     nghttp2_inbound_frame *iframe = &(*session_ptr)->iframe;
 
     if (server &&
-        ((*session_ptr)->opt_flags & NGHTTP2_OPTMASK_NO_RECV_CLIENT_PREFACE) ==
+        ((*session_ptr)->opt_flags & NGHTTP2_OPTMASK_NO_RECV_CLIENT_MAGIC) ==
             0) {
-      iframe->state = NGHTTP2_IB_READ_CLIENT_PREFACE;
-      iframe->payloadleft = NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN;
+      iframe->state = NGHTTP2_IB_READ_CLIENT_MAGIC;
+      iframe->payloadleft = NGHTTP2_CLIENT_MAGIC_LEN;
     } else {
       iframe->state = NGHTTP2_IB_READ_FIRST_SETTINGS;
     }
+
+    if (!server) {
+      (*session_ptr)->aob.state = NGHTTP2_OB_SEND_CLIENT_MAGIC;
+      nghttp2_bufs_add(&(*session_ptr)->aob.framebufs, NGHTTP2_CLIENT_MAGIC,
+                       NGHTTP2_CLIENT_MAGIC_LEN);
+    }
   }
 
   return 0;
@@ -2979,6 +2985,25 @@ static ssize_t nghttp2_session_mem_send_internal(nghttp2_session *session,
 
       break;
     }
+    case NGHTTP2_OB_SEND_CLIENT_MAGIC: {
+      size_t datalen;
+      nghttp2_buf *buf;
+
+      buf = &framebufs->cur->buf;
+
+      if (buf->pos == buf->last) {
+        DEBUGF(fprintf(stderr, "send: end transmission of client magic\n"));
+        active_outbound_item_reset(aob, mem);
+        break;
+      }
+
+      *data_ptr = buf->pos;
+      datalen = nghttp2_buf_len(buf);
+
+      buf->pos += datalen;
+
+      return datalen;
+    }
     }
   }
 }
@@ -2993,14 +3018,16 @@ ssize_t nghttp2_session_mem_send(nghttp2_session *session,
     return len;
   }
 
-  /* We have to call session_after_frame_sent1 here to handle stream
-     closure upon transmission of frames.  Otherwise, END_STREAM may
-     be reached to client before we call nghttp2_session_mem_send
-     again and we may get exceeding number of incoming streams. */
-  rv = session_after_frame_sent1(session);
-  if (rv < 0) {
-    assert(nghttp2_is_fatal(rv));
-    return (ssize_t)rv;
+  if (session->aob.item) {
+    /* We have to call session_after_frame_sent1 here to handle stream
+       closure upon transmission of frames.  Otherwise, END_STREAM may
+       be reached to client before we call nghttp2_session_mem_send
+       again and we may get exceeding number of incoming streams. */
+    rv = session_after_frame_sent1(session);
+    if (rv < 0) {
+      assert(nghttp2_is_fatal(rv));
+      return (ssize_t)rv;
+    }
   }
 
   return len;
@@ -4907,14 +4934,13 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in,
 
   for (;;) {
     switch (iframe->state) {
-    case NGHTTP2_IB_READ_CLIENT_PREFACE:
+    case NGHTTP2_IB_READ_CLIENT_MAGIC:
       readlen = nghttp2_min(inlen, iframe->payloadleft);
 
-      if (memcmp(NGHTTP2_CLIENT_CONNECTION_PREFACE +
-                     NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN -
+      if (memcmp(NGHTTP2_CLIENT_MAGIC + NGHTTP2_CLIENT_MAGIC_LEN -
                      iframe->payloadleft,
                  in, readlen) != 0) {
-        return NGHTTP2_ERR_BAD_PREFACE;
+        return NGHTTP2_ERR_BAD_CLIENT_MAGIC;
       }
 
       iframe->payloadleft -= readlen;
diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h
index ea532262..9d14c8ee 100644
--- a/lib/nghttp2_session.h
+++ b/lib/nghttp2_session.h
@@ -46,14 +46,15 @@
  */
 typedef enum {
   NGHTTP2_OPTMASK_NO_AUTO_WINDOW_UPDATE = 1 << 0,
-  NGHTTP2_OPTMASK_NO_RECV_CLIENT_PREFACE = 1 << 1,
+  NGHTTP2_OPTMASK_NO_RECV_CLIENT_MAGIC = 1 << 1,
   NGHTTP2_OPTMASK_NO_HTTP_MESSAGING = 1 << 2,
 } nghttp2_optmask;
 
 typedef enum {
   NGHTTP2_OB_POP_ITEM,
   NGHTTP2_OB_SEND_DATA,
-  NGHTTP2_OB_SEND_NO_COPY
+  NGHTTP2_OB_SEND_NO_COPY,
+  NGHTTP2_OB_SEND_CLIENT_MAGIC
 } nghttp2_outbound_state;
 
 typedef struct {
@@ -69,7 +70,7 @@ typedef struct {
 /* Internal state when receiving incoming frame */
 typedef enum {
   /* Receiving frame header */
-  NGHTTP2_IB_READ_CLIENT_PREFACE,
+  NGHTTP2_IB_READ_CLIENT_MAGIC,
   NGHTTP2_IB_READ_FIRST_SETTINGS,
   NGHTTP2_IB_READ_HEAD,
   NGHTTP2_IB_READ_NBYTE,
diff --git a/python/nghttp2.pyx b/python/nghttp2.pyx
index 10b12759..c6b9b66c 100644
--- a/python/nghttp2.pyx
+++ b/python/nghttp2.pyx
@@ -1477,8 +1477,6 @@ if asyncio:
                    cnghttp2.NGHTTP2_PROTO_VERSION_ID:
                     self.transport.abort()
 
-            # Send preamble
-            self.transport.write(cnghttp2.NGHTTP2_CLIENT_CONNECTION_PREFACE)
             self.http2 = _HTTP2ClientSessionCore(self.transport)
 
 	    # Clear pending requests
diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index 1aa2aea7..b9bb557f 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -431,7 +431,7 @@ int Http2Handler::read_clear() {
 
     rv = nghttp2_session_mem_recv(session_, buf.data(), nread);
     if (rv < 0) {
-      if (rv != NGHTTP2_ERR_BAD_PREFACE) {
+      if (rv != NGHTTP2_ERR_BAD_CLIENT_MAGIC) {
         std::cerr << "nghttp2_session_mem_recv() returned error: "
                   << nghttp2_strerror(rv) << std::endl;
       }
@@ -558,7 +558,7 @@ int Http2Handler::read_tls() {
 
     rv = nghttp2_session_mem_recv(session_, buf.data(), nread);
     if (rv < 0) {
-      if (rv != NGHTTP2_ERR_BAD_PREFACE) {
+      if (rv != NGHTTP2_ERR_BAD_CLIENT_MAGIC) {
         std::cerr << "nghttp2_session_mem_recv() returned error: "
                   << nghttp2_strerror(rv) << std::endl;
       }
diff --git a/src/asio_client_session_impl.cc b/src/asio_client_session_impl.cc
index 844b1957..e705105d 100644
--- a/src/asio_client_session_impl.cc
+++ b/src/asio_client_session_impl.cc
@@ -75,10 +75,6 @@ void session_impl::connected(tcp::resolver::iterator endpoint_it) {
 
   socket().set_option(boost::asio::ip::tcp::no_delay(true));
 
-  std::copy_n(NGHTTP2_CLIENT_CONNECTION_PREFACE,
-              NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN, std::begin(wb_));
-  wblen_ = NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN;
-
   do_write();
   do_read();
 
diff --git a/src/h2load_http2_session.cc b/src/h2load_http2_session.cc
index bc658380..0f0ef0f6 100644
--- a/src/h2load_http2_session.cc
+++ b/src/h2load_http2_session.cc
@@ -202,12 +202,6 @@ void Http2Session::on_connect() {
                                  extra_connection_window);
   }
 
-  auto &wb = client_->wb;
-  assert(wb.wleft() >= NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
-
-  wb.write(NGHTTP2_CLIENT_CONNECTION_PREFACE,
-           NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
-
   client_->signal_write();
 }
 
diff --git a/src/nghttp.cc b/src/nghttp.cc
index fa57a99e..34f84820 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -962,9 +962,6 @@ int HttpClient::connection_made() {
       request_done(stream_user_data);
     }
   }
-  // Send connection header here
-  wb.write(NGHTTP2_CLIENT_CONNECTION_PREFACE,
-           NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
   // If upgrade succeeds, the SETTINGS value sent with
   // HTTP2-Settings header field has already been submitted to
   // session object.
diff --git a/src/shrpx.cc b/src/shrpx.cc
index 4b64ce39..8904ce13 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -904,7 +904,7 @@ void fill_default_config() {
 
   nghttp2_option_new(&mod_config()->http2_option);
   nghttp2_option_set_no_auto_window_update(get_config()->http2_option, 1);
-  nghttp2_option_set_no_recv_client_preface(get_config()->http2_option, 1);
+  nghttp2_option_set_no_recv_client_magic(get_config()->http2_option, 1);
 
   nghttp2_option_new(&mod_config()->http2_client_option);
   nghttp2_option_set_no_auto_window_update(get_config()->http2_client_option,
diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index c8065bb4..58d9eb74 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -279,8 +279,7 @@ int ClientHandler::upstream_write() {
 
 int ClientHandler::upstream_http2_connhd_read() {
   auto nread = std::min(left_connhd_len_, rb_.rleft());
-  if (memcmp(NGHTTP2_CLIENT_CONNECTION_PREFACE +
-                 NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN - left_connhd_len_,
+  if (memcmp(NGHTTP2_CLIENT_MAGIC + NGHTTP2_CLIENT_MAGIC_LEN - left_connhd_len_,
              rb_.pos, nread) != 0) {
     // There is no downgrade path here. Just drop the connection.
     if (LOG_ENABLED(INFO)) {
@@ -309,8 +308,7 @@ int ClientHandler::upstream_http2_connhd_read() {
 
 int ClientHandler::upstream_http1_connhd_read() {
   auto nread = std::min(left_connhd_len_, rb_.rleft());
-  if (memcmp(NGHTTP2_CLIENT_CONNECTION_PREFACE +
-                 NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN - left_connhd_len_,
+  if (memcmp(NGHTTP2_CLIENT_MAGIC + NGHTTP2_CLIENT_MAGIC_LEN - left_connhd_len_,
              rb_.pos, nread) != 0) {
     if (LOG_ENABLED(INFO)) {
       CLOG(INFO, this) << "This is HTTP/1.1 connection, "
@@ -318,7 +316,7 @@ int ClientHandler::upstream_http1_connhd_read() {
     }
 
     // Reset header length for later HTTP/2 upgrade
-    left_connhd_len_ = NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN;
+    left_connhd_len_ = NGHTTP2_CLIENT_MAGIC_LEN;
     on_read_ = &ClientHandler::upstream_read;
     on_write_ = &ClientHandler::upstream_write;
 
@@ -362,7 +360,7 @@ ClientHandler::ClientHandler(Worker *worker, int fd, SSL *ssl,
             get_config()->read_burst, writecb, readcb, timeoutcb, this),
       ipaddr_(ipaddr), port_(port), worker_(worker),
       http2session_(worker_->next_http2_session()),
-      left_connhd_len_(NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN),
+      left_connhd_len_(NGHTTP2_CLIENT_MAGIC_LEN),
       should_close_after_write_(false) {
 
   ++worker_->get_worker_stat()->num_connections;
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index a73c91c5..5fc5f7e3 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -1278,13 +1278,6 @@ int Http2Session::connection_made() {
     }
   }
 
-  auto nwrite = wb_.write(NGHTTP2_CLIENT_CONNECTION_PREFACE,
-                          NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
-  if (nwrite != NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN) {
-    SSLOG(FATAL, this) << "buffer is too small to send connection preface";
-    return -1;
-  }
-
   auto must_terminate = !get_config()->downstream_no_tls &&
                         !ssl::check_http2_requirement(conn_.tls.ssl);
 
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 64af8afa..121db248 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -769,7 +769,7 @@ int Http2Upstream::on_read() {
   if (rb->rleft()) {
     rv = nghttp2_session_mem_recv(session_, rb->pos, rb->rleft());
     if (rv < 0) {
-      if (rv != NGHTTP2_ERR_BAD_PREFACE) {
+      if (rv != NGHTTP2_ERR_BAD_CLIENT_MAGIC) {
         ULOG(ERROR, this) << "nghttp2_session_recv() returned error: "
                           << nghttp2_strerror(rv);
       }
diff --git a/tests/main.c b/tests/main.c
index 9b9e8e63..396c0081 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -41,7 +41,7 @@
 #include "nghttp2_helper_test.h"
 #include "nghttp2_buf_test.h"
 
-extern int nghttp2_enable_strict_connection_preface_check;
+extern int nghttp2_enable_strict_preface;
 
 static int init_suite1(void) { return 0; }
 
@@ -51,7 +51,7 @@ int main(int argc _U_, char *argv[] _U_) {
   CU_pSuite pSuite = NULL;
   unsigned int num_tests_failed;
 
-  nghttp2_enable_strict_connection_preface_check = 0;
+  nghttp2_enable_strict_preface = 0;
 
   /* initialize the CUnit test registry */
   if (CUE_SUCCESS != CU_initialize_registry())
@@ -250,8 +250,8 @@ int main(int argc _U_, char *argv[] _U_) {
                    test_nghttp2_session_graceful_shutdown) ||
       !CU_add_test(pSuite, "session_on_header_temporal_failure",
                    test_nghttp2_session_on_header_temporal_failure) ||
-      !CU_add_test(pSuite, "session_recv_client_preface",
-                   test_nghttp2_session_recv_client_preface) ||
+      !CU_add_test(pSuite, "session_recv_client_magic",
+                   test_nghttp2_session_recv_client_magic) ||
       !CU_add_test(pSuite, "session_delete_data_item",
                    test_nghttp2_session_delete_data_item) ||
       !CU_add_test(pSuite, "session_open_idle_stream",
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 4e77019b..8721eeae 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -36,7 +36,7 @@
 #include "nghttp2_test_helper.h"
 #include "nghttp2_priority_spec.h"
 
-extern int nghttp2_enable_strict_connection_preface_check;
+extern int nghttp2_enable_strict_preface;
 
 #define OB_CTRL(ITEM) nghttp2_outbound_item_get_ctrl_frame(ITEM)
 #define OB_CTRL_TYPE(ITEM) nghttp2_outbound_item_get_ctrl_frame_type(ITEM)
@@ -6722,27 +6722,25 @@ void test_nghttp2_session_on_header_temporal_failure(void) {
   nghttp2_session_del(session);
 }
 
-void test_nghttp2_session_recv_client_preface(void) {
+void test_nghttp2_session_recv_client_magic(void) {
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
   ssize_t rv;
   nghttp2_frame ping_frame;
   uint8_t buf[16];
 
-  /* enable global nghttp2_enable_strict_connection_preface_check
-     here */
-  nghttp2_enable_strict_connection_preface_check = 1;
+  /* enable global nghttp2_enable_strict_preface here */
+  nghttp2_enable_strict_preface = 1;
 
   memset(&callbacks, 0, sizeof(callbacks));
 
   /* Check success case */
   nghttp2_session_server_new(&session, &callbacks, NULL);
 
-  rv = nghttp2_session_mem_recv(
-      session, (const uint8_t *)NGHTTP2_CLIENT_CONNECTION_PREFACE,
-      NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
+  rv = nghttp2_session_mem_recv(session, (const uint8_t *)NGHTTP2_CLIENT_MAGIC,
+                                NGHTTP2_CLIENT_MAGIC_LEN);
 
-  CU_ASSERT(rv == NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN);
+  CU_ASSERT(rv == NGHTTP2_CLIENT_MAGIC_LEN);
   CU_ASSERT(NGHTTP2_IB_READ_FIRST_SETTINGS == session->iframe.state);
 
   /* Receiving PING is error because we want SETTINGS. */
@@ -6762,24 +6760,22 @@ void test_nghttp2_session_recv_client_preface(void) {
   /* Check bad case */
   nghttp2_session_server_new(&session, &callbacks, NULL);
 
-  /* Feed preface with one byte less */
-  rv = nghttp2_session_mem_recv(
-      session, (const uint8_t *)NGHTTP2_CLIENT_CONNECTION_PREFACE,
-      NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN - 1);
+  /* Feed magic with one byte less */
+  rv = nghttp2_session_mem_recv(session, (const uint8_t *)NGHTTP2_CLIENT_MAGIC,
+                                NGHTTP2_CLIENT_MAGIC_LEN - 1);
 
-  CU_ASSERT(rv == NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN - 1);
-  CU_ASSERT(NGHTTP2_IB_READ_CLIENT_PREFACE == session->iframe.state);
+  CU_ASSERT(rv == NGHTTP2_CLIENT_MAGIC_LEN - 1);
+  CU_ASSERT(NGHTTP2_IB_READ_CLIENT_MAGIC == session->iframe.state);
   CU_ASSERT(1 == session->iframe.payloadleft);
 
   rv = nghttp2_session_mem_recv(session, (const uint8_t *)"\0", 1);
 
-  CU_ASSERT(NGHTTP2_ERR_BAD_PREFACE == rv);
+  CU_ASSERT(NGHTTP2_ERR_BAD_CLIENT_MAGIC == rv);
 
   nghttp2_session_del(session);
 
-  /* disable global nghttp2_enable_strict_connection_preface_check
-     here */
-  nghttp2_enable_strict_connection_preface_check = 0;
+  /* disable global nghttp2_enable_strict_preface here */
+  nghttp2_enable_strict_preface = 0;
 }
 
 void test_nghttp2_session_delete_data_item(void) {
diff --git a/tests/nghttp2_session_test.h b/tests/nghttp2_session_test.h
index b6fe967d..406cfb78 100644
--- a/tests/nghttp2_session_test.h
+++ b/tests/nghttp2_session_test.h
@@ -118,7 +118,7 @@ void test_nghttp2_session_detach_idle_stream(void);
 void test_nghttp2_session_large_dep_tree(void);
 void test_nghttp2_session_graceful_shutdown(void);
 void test_nghttp2_session_on_header_temporal_failure(void);
-void test_nghttp2_session_recv_client_preface(void);
+void test_nghttp2_session_recv_client_magic(void);
 void test_nghttp2_session_delete_data_item(void);
 void test_nghttp2_session_open_idle_stream(void);
 void test_nghttp2_session_cancel_reserved_remote(void);