diff --git a/lib/includes/spdylay/spdylay.h b/lib/includes/spdylay/spdylay.h
index 3a6d6cf7..5dfcacce 100644
--- a/lib/includes/spdylay/spdylay.h
+++ b/lib/includes/spdylay/spdylay.h
@@ -195,7 +195,7 @@ typedef void (*spdylay_on_ping_recv_callback)
  * whose flags contains SPDYLAY_FLAG_FIN.
  */
 typedef void (*spdylay_on_data_chunk_recv_callback)
-(spdylay_session *session, int32_t stream_id, uint8_t flags,
+(spdylay_session *session, uint8_t flags, int32_t stream_id,
  const uint8_t *data, size_t len, void *user_data);
 
 /*
@@ -203,7 +203,7 @@ typedef void (*spdylay_on_data_chunk_recv_callback)
  * data it contains are received by spdylay_on_data_recv_callback.
  */
 typedef void (*spdylay_on_data_recv_callback)
-(spdylay_session *session, int32_t stream_id, uint8_t flags, int32_t length,
+(spdylay_session *session, uint8_t flags, int32_t stream_id, int32_t length,
  void *user_data);
 
 typedef struct {
diff --git a/lib/spdylay_session.c b/lib/spdylay_session.c
index 82b48aef..2a9e223c 100644
--- a/lib/spdylay_session.c
+++ b/lib/spdylay_session.c
@@ -892,7 +892,7 @@ int spdylay_session_process_data_frame(spdylay_session *session)
     length = spdylay_get_uint32(&session->iframe.headbuf[4]) &
       SPDYLAY_LENGTH_MASK;
     session->callbacks.on_data_recv_callback
-      (session, stream_id, flags, length, session->user_data);
+      (session, flags, stream_id, length, session->user_data);
   }
   return 0;
 }
@@ -962,8 +962,9 @@ int spdylay_session_recv(spdylay_session *session)
         stream_id = spdylay_get_uint32(session->iframe.headbuf) &
           SPDYLAY_STREAM_ID_MASK;
         flags = session->iframe.headbuf[4];
-        session->callbacks.on_data_chunk_recv_callback(session, stream_id,
+        session->callbacks.on_data_chunk_recv_callback(session,
                                                        flags,
+                                                       stream_id,
                                                        session->ibuf.mark,
                                                        readlen,
                                                        session->user_data);