diff --git a/examples/client.c b/examples/client.c
index 5196687f..6fc2f9e7 100644
--- a/examples/client.c
+++ b/examples/client.c
@@ -228,7 +228,7 @@ static ssize_t recv_callback(nghttp2_session *session,
  * (nghttp2_submit_request).
  */
 static int before_frame_send_callback(nghttp2_session *session,
-                                      nghttp2_frame *frame,
+                                      const nghttp2_frame *frame,
                                       void *user_data)
 {
   if(frame->hd.type == NGHTTP2_HEADERS &&
@@ -245,7 +245,7 @@ static int before_frame_send_callback(nghttp2_session *session,
 }
 
 static int on_frame_send_callback(nghttp2_session *session,
-                                  nghttp2_frame *frame, void *user_data)
+                                  const nghttp2_frame *frame, void *user_data)
 {
   size_t i;
   switch(frame->hd.type) {
@@ -272,7 +272,7 @@ static int on_frame_send_callback(nghttp2_session *session,
 }
 
 static int on_frame_recv_callback(nghttp2_session *session,
-                                  nghttp2_frame *frame, void *user_data)
+                                  const nghttp2_frame *frame, void *user_data)
 {
   size_t i;
   switch(frame->hd.type) {
@@ -311,8 +311,8 @@ static int on_frame_recv_callback(nghttp2_session *session,
  */
 static int on_stream_close_callback(nghttp2_session *session,
                                     int32_t stream_id,
-                                     nghttp2_error_code error_code,
-                                     void *user_data)
+                                    nghttp2_error_code error_code,
+                                    void *user_data)
 {
   struct Request *req;
   req = nghttp2_session_get_stream_user_data(session, stream_id);
diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 9e582403..eaeac330 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -786,7 +786,7 @@ typedef ssize_t (*nghttp2_recv_callback)
  * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_on_frame_recv_callback)
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);
 
 /**
  * @functypedef
@@ -803,8 +803,8 @@ typedef int (*nghttp2_on_frame_recv_callback)
  * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_on_invalid_frame_recv_callback)
-(nghttp2_session *session, nghttp2_frame *frame, nghttp2_error_code error_code,
- void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame,
+ nghttp2_error_code error_code, void *user_data);
 
 /**
  * @functypedef
@@ -857,7 +857,7 @@ typedef int (*nghttp2_on_data_recv_callback)
  * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_before_frame_send_callback)
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);
 
 /**
  * @functypedef
@@ -870,7 +870,7 @@ typedef int (*nghttp2_before_frame_send_callback)
  * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_on_frame_send_callback)
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);
 
 /**
  * @functypedef
@@ -886,7 +886,7 @@ typedef int (*nghttp2_on_frame_send_callback)
  * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
  */
 typedef int (*nghttp2_on_frame_not_send_callback)
-(nghttp2_session *session, nghttp2_frame *frame, int lib_error_code,
+(nghttp2_session *session, const nghttp2_frame *frame, int lib_error_code,
  void *user_data);
 
 /**
diff --git a/src/HttpServer.cc b/src/HttpServer.cc
index e7eb58b6..28aad538 100644
--- a/src/HttpServer.cc
+++ b/src/HttpServer.cc
@@ -686,7 +686,7 @@ const char *REQUIRED_HEADERS[] = {
 
 namespace {
 int hd_on_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   auto hd = reinterpret_cast<Http2Handler*>(user_data);
   if(hd->get_config()->verbose) {
@@ -741,7 +741,7 @@ int htdocs_on_request_recv_callback
 
 namespace {
 int hd_on_frame_send_callback
-(nghttp2_session *session, nghttp2_frame *frame,
+(nghttp2_session *session, const nghttp2_frame *frame,
  void *user_data)
 {
   auto hd = reinterpret_cast<Http2Handler*>(user_data);
diff --git a/src/app_helper.cc b/src/app_helper.cc
index aff71857..9035c3e4 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -235,7 +235,7 @@ const char* frame_name_ansi_esc(print_type ptype)
 } // namespace
 
 namespace {
-void print_frame(print_type ptype, nghttp2_frame *frame)
+void print_frame(print_type ptype, const nghttp2_frame *frame)
 {
   printf("%s%s%s frame ",
          frame_name_ansi_esc(ptype),
@@ -324,7 +324,7 @@ void print_frame(print_type ptype, nghttp2_frame *frame)
 } // namespace
 
 int on_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   print_timer();
   printf(" recv ");
@@ -334,7 +334,7 @@ int on_frame_recv_callback
 }
 
 int on_invalid_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame,
+(nghttp2_session *session, const nghttp2_frame *frame,
  nghttp2_error_code error_code, void *user_data)
 {
   print_timer();
@@ -392,7 +392,7 @@ int on_unknown_frame_recv_callback(nghttp2_session *session,
 }
 
 int on_frame_send_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   print_timer();
   printf(" send ");
diff --git a/src/app_helper.h b/src/app_helper.h
index bf331771..6860e433 100644
--- a/src/app_helper.h
+++ b/src/app_helper.h
@@ -40,10 +40,10 @@ namespace nghttp2 {
 void print_nv(char **nv);
 
 int on_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);
 
 int on_invalid_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame,
+(nghttp2_session *session, const nghttp2_frame *frame,
  nghttp2_error_code error_code, void *user_data);
 
 int on_frame_recv_parse_error_callback(nghttp2_session *session,
@@ -62,7 +62,7 @@ int on_unknown_frame_recv_callback(nghttp2_session *session,
                                    void *user_data);
 
 int on_frame_send_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data);
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data);
 
 int on_data_recv_callback
 (nghttp2_session *session, uint16_t length, uint8_t flags, int32_t stream_id,
diff --git a/src/nghttp.cc b/src/nghttp.cc
index 3317e6b0..a689920c 100644
--- a/src/nghttp.cc
+++ b/src/nghttp.cc
@@ -979,7 +979,7 @@ void check_stream_id(nghttp2_session *session, int32_t stream_id,
 } // namespace
 
 int on_frame_send_callback2
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   if(frame->hd.type == NGHTTP2_HEADERS &&
      frame->headers.cat == NGHTTP2_HCAT_REQUEST) {
@@ -992,7 +992,7 @@ int on_frame_send_callback2
 }
 
 void check_response_header
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   if(frame->hd.type != NGHTTP2_HEADERS ||
      frame->headers.cat != NGHTTP2_HCAT_RESPONSE) {
@@ -1027,7 +1027,7 @@ void check_response_header
 }
 
 int on_frame_recv_callback2
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   if(frame->hd.type == NGHTTP2_HEADERS &&
      frame->headers.cat == NGHTTP2_HCAT_RESPONSE) {
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 78a41305..ee19496d 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -174,7 +174,7 @@ int Http2Upstream::upgrade_upstream(HttpsUpstream *http)
 
 namespace {
 int on_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   auto upstream = reinterpret_cast<Http2Upstream*>(user_data);
   switch(frame->hd.type) {
@@ -332,7 +332,7 @@ int on_data_chunk_recv_callback(nghttp2_session *session,
 
 namespace {
 int on_frame_not_send_callback(nghttp2_session *session,
-                               nghttp2_frame *frame,
+                               const nghttp2_frame *frame,
                                int lib_error_code, void *user_data)
 {
   auto upstream = reinterpret_cast<Http2Upstream*>(user_data);
diff --git a/src/shrpx_spdy_session.cc b/src/shrpx_spdy_session.cc
index 3d3bae6e..6393b38a 100644
--- a/src/shrpx_spdy_session.cc
+++ b/src/shrpx_spdy_session.cc
@@ -724,7 +724,7 @@ int on_stream_close_callback
 
 namespace {
 int on_frame_recv_callback
-(nghttp2_session *session, nghttp2_frame *frame, void *user_data)
+(nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
 {
   int rv;
   auto spdy = reinterpret_cast<SpdySession*>(user_data);
@@ -947,7 +947,7 @@ int on_data_chunk_recv_callback(nghttp2_session *session,
 
 namespace {
 int before_frame_send_callback(nghttp2_session *session,
-                               nghttp2_frame *frame,
+                               const nghttp2_frame *frame,
                                void *user_data)
 {
   if(frame->hd.type == NGHTTP2_HEADERS &&
@@ -972,8 +972,8 @@ int before_frame_send_callback(nghttp2_session *session,
 
 namespace {
 int on_frame_not_send_callback(nghttp2_session *session,
-                                nghttp2_frame *frame,
-                                int lib_error_code, void *user_data)
+                               const nghttp2_frame *frame,
+                               int lib_error_code, void *user_data)
 {
   auto spdy = reinterpret_cast<SpdySession*>(user_data);
   SSLOG(WARNING, spdy) << "Failed to send control frame type="
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 92c92031..37b5be77 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -109,8 +109,8 @@ static ssize_t scripted_recv_callback(nghttp2_session *session,
 }
 
 static ssize_t eof_recv_callback(nghttp2_session *session,
-                                      uint8_t* data, size_t len, int flags,
-                                      void *user_data)
+                                 uint8_t* data, size_t len, int flags,
+                                 void *user_data)
 {
   return NGHTTP2_ERR_EOF;
 }
@@ -127,7 +127,7 @@ static ssize_t accumulator_send_callback(nghttp2_session *session,
 }
 
 static int on_frame_recv_callback(nghttp2_session *session,
-                                  nghttp2_frame *frame,
+                                  const nghttp2_frame *frame,
                                   void *user_data)
 {
   my_user_data *ud = (my_user_data*)user_data;
@@ -136,7 +136,7 @@ static int on_frame_recv_callback(nghttp2_session *session,
 }
 
 static int on_invalid_frame_recv_callback(nghttp2_session *session,
-                                          nghttp2_frame *frame,
+                                          const nghttp2_frame *frame,
                                           nghttp2_error_code error_code,
                                           void *user_data)
 {
@@ -146,7 +146,7 @@ static int on_invalid_frame_recv_callback(nghttp2_session *session,
 }
 
 static int on_frame_send_callback(nghttp2_session *session,
-                                  nghttp2_frame *frame,
+                                  const nghttp2_frame *frame,
                                   void *user_data)
 {
   my_user_data *ud = (my_user_data*)user_data;
@@ -156,7 +156,7 @@ static int on_frame_send_callback(nghttp2_session *session,
 }
 
 static int on_frame_not_send_callback(nghttp2_session *session,
-                                      nghttp2_frame *frame,
+                                      const nghttp2_frame *frame,
                                       int lib_error,
                                       void *user_data)
 {