diff --git a/include/hexagram/pcapng.h b/include/hexagram/pcapng.h
index 39e52ad..f24390c 100644
--- a/include/hexagram/pcapng.h
+++ b/include/hexagram/pcapng.h
@@ -21,23 +21,27 @@ typedef struct _hexagram_pcapng_stream {
 
 typedef ssize_t (hexagram_pcapng_block_handler)(hexagram_pcapng_stream *,
                                                 uint32_t type,
-                                                size_t length);
+                                                size_t length,
+                                                void *data);
 
 typedef ssize_t (hexagram_pcapng_option_handler)(hexagram_pcapng_stream *,
                                                  uint32_t type,
                                                  uint16_t code,
-                                                 uint16_t length);
+                                                 uint16_t length,
+                                                 void *data);
 
 hexagram_pcapng_stream *hexagram_pcapng_stream_open_fd(int fd);
 
 void hexagram_pcapng_stream_destroy(hexagram_pcapng_stream *stream);
 
-ssize_t hexagram_pcapng_stream_read(hexagram_pcapng_stream *stream,
-                                    hexagram_pcapng_block_handler *handler);
-
 ssize_t hexagram_pcapng_read_options(hexagram_pcapng_stream *stream,
                                      hexagram_pcapng_option_handler *handler,
                                      uint32_t type,
-                                     size_t len);
+                                     size_t len,
+                                     void *data);
+
+ssize_t hexagram_pcapng_stream_read(hexagram_pcapng_stream *stream,
+                                    hexagram_pcapng_block_handler *handler,
+                                    void *data);
 
 #endif /* _HEXAGRAM_PCAPNG_H */