diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 24a54a5..23caa0c 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -617,7 +617,8 @@
 	ata_tf_to_fis(&qc->tf, pp->cmd_tbl, 0);
 	if (is_atapi) {
 		memset(pp->cmd_tbl + AHCI_CMD_TBL_CDB, 0, 32);
-		memcpy(pp->cmd_tbl + AHCI_CMD_TBL_CDB, qc->cdb, ap->cdb_len);
+		memcpy(pp->cmd_tbl + AHCI_CMD_TBL_CDB, qc->cdb,
+		       qc->dev->cdb_len);
 	}
 
 	n_elem = 0;