diff --git a/sound/firewire/amdtp-am824.c b/sound/firewire/amdtp-am824.c
index bebddc60fde8..99654e7eb2d4 100644
--- a/sound/firewire/amdtp-am824.c
+++ b/sound/firewire/amdtp-am824.c
@@ -388,7 +388,7 @@ static void read_midi_messages(struct amdtp_stream *s,
 	u8 *b;
 
 	for (f = 0; f < frames; f++) {
-		port = (s->data_block_counter + f) % 8;
+		port = (8 - s->tx_first_dbc + s->data_block_counter + f) % 8;
 		b = (u8 *)&buffer[p->midi_position];
 
 		len = b[0] - 0x80;