diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index 70b58fe9e5b1..a7f0139c3aae 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -865,7 +865,7 @@ static void sil24_qc_prep(struct ata_queued_cmd *qc)
 	} else {
 		prb = &cb->atapi.prb;
 		sge = cb->atapi.sge;
-		memset(cb->atapi.cdb, 0, 32);
+		memset(cb->atapi.cdb, 0, sizeof(cb->atapi.cdb));
 		memcpy(cb->atapi.cdb, qc->cdb, qc->dev->cdb_len);
 
 		if (ata_is_data(qc->tf.protocol)) {