diff --git a/profiles/midi/libmidi.c b/profiles/midi/libmidi.c
index ac090b5..4b4df79 100644
--- a/profiles/midi/libmidi.c
+++ b/profiles/midi/libmidi.c
@@ -52,6 +52,13 @@ inline static uint8_t buffer_reverse_get(struct midi_buffer *buffer, size_t i)
 	return buffer->data[buffer->len - (i + 1)];
 }
 
+inline static void buffer_reverse_set(struct midi_buffer *buffer, size_t i,
+                                      const uint8_t byte)
+{
+	MIDI_ASSERT(buffer->len > i);
+	buffer->data[buffer->len - (i + 1)] = byte;
+}
+
 inline static size_t parser_get_available_size(struct midi_write_parser *parser)
 {
 	return parser->stream_size - parser->midi_stream.len;
@@ -314,7 +321,7 @@ static size_t handle_end_of_sysex(struct midi_read_parser *parser,
 	time_low = buffer_reverse_get(&parser->sysex_stream, 0) & 0x7F;
 
 	/* Remove timestamp byte */
-	parser->sysex_stream.data[parser->sysex_stream.len - 1] = 0xF7;
+	buffer_reverse_set(&parser->sysex_stream, 0, 0xF7);
 
 	/* Update event */
 	update_ev_timestamp(parser, ev, time_low);