diff --git a/drivers/staging/rts5139/ms.c b/drivers/staging/rts5139/ms.c
index b0e9071c8e52..02aad2d242cb 100644
--- a/drivers/staging/rts5139/ms.c
+++ b/drivers/staging/rts5139/ms.c
@@ -3864,7 +3864,7 @@ static int ms_rw_multi_sector(struct scsi_cmnd *srb, struct rts51x_chip *chip,
 	log_blk = (u16) (start_sector >> ms_card->block_shift);
 	start_page = (u8) (start_sector & ms_card->page_off);
 
-	for (seg_no = 0; seg_no < sizeof(ms_start_idx) / 2; seg_no++) {
+	for (seg_no = 0; seg_no < ARRAY_SIZE(ms_start_idx) - 1; seg_no++) {
 		if (log_blk < ms_start_idx[seg_no + 1])
 			break;
 	}
@@ -4020,7 +4020,8 @@ static int ms_rw_multi_sector(struct scsi_cmnd *srb, struct rts51x_chip *chip,
 
 		log_blk++;
 
-		for (seg_no = 0; seg_no < sizeof(ms_start_idx) / 2; seg_no++) {
+		for (seg_no = 0; seg_no < ARRAY_SIZE(ms_start_idx) - 1;
+				seg_no++) {
 			if (log_blk < ms_start_idx[seg_no + 1])
 				break;
 		}