diff --git a/drivers/mtd/nftlcore.c b/drivers/mtd/nftlcore.c
index 665d3eba2f47d2ee62fab71c12c3420cc591fd91..1002e18829966256bb77833f67501c6871d7d4ce 100644
--- a/drivers/mtd/nftlcore.c
+++ b/drivers/mtd/nftlcore.c
@@ -135,16 +135,17 @@ static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
 int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 		  size_t *retlen, uint8_t *buf)
 {
+	loff_t mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = len;
 	ops.oobbuf = buf;
 	ops.datbuf = NULL;
 
-	res = mtd->read_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->read_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.oobretlen;
 	return res;
 }
@@ -155,16 +156,17 @@ int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 		   size_t *retlen, uint8_t *buf)
 {
+	loff_t mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = len;
 	ops.oobbuf = buf;
 	ops.datbuf = NULL;
 
-	res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->write_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.oobretlen;
 	return res;
 }
@@ -177,17 +179,18 @@ int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 static int nftl_write(struct mtd_info *mtd, loff_t offs, size_t len,
 		      size_t *retlen, uint8_t *buf, uint8_t *oob)
 {
+	loff_t mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = mtd->oobsize;
 	ops.oobbuf = oob;
 	ops.datbuf = buf;
 	ops.len = len;
 
-	res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->write_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.retlen;
 	return res;
 }