diff --git a/drivers/mtd/core.c b/drivers/mtd/core.c
index fc2ac0033..6db1c6db3 100644
--- a/drivers/mtd/core.c
+++ b/drivers/mtd/core.c
@@ -236,6 +236,7 @@ int mtd_ioctl(struct cdev *cdev, int request, void *buf)
 		user->erasesize	= mtd->erasesize;
 		user->writesize	= mtd->writesize;
 		user->oobsize	= mtd->oobsize;
+		user->subpagesize = mtd->writesize >> mtd->subpage_sft;
 		user->mtd	= mtd;
 		/* The below fields are obsolete */
 		user->ecctype	= -1;
diff --git a/fs/devfs-core.c b/fs/devfs-core.c
index a92d4347f..44f0169e6 100644
--- a/fs/devfs-core.c
+++ b/fs/devfs-core.c
@@ -171,6 +171,7 @@ static int partition_ioctl(struct cdev *cdev, int request, void *buf)
 			user->erasesize	= cdev->mtd->erasesize;
 			user->writesize	= cdev->mtd->writesize;
 			user->oobsize	= cdev->mtd->oobsize;
+			user->subpagesize = cdev->mtd->writesize >> cdev->mtd->subpage_sft;
 			user->mtd	= cdev->mtd;
 			/* The below fields are obsolete */
 			user->ecctype	= -1;
diff --git a/include/linux/mtd/mtd-abi.h b/include/linux/mtd/mtd-abi.h
index fa8e36f13..11d51e274 100644
--- a/include/linux/mtd/mtd-abi.h
+++ b/include/linux/mtd/mtd-abi.h
@@ -82,6 +82,7 @@ struct mtd_info_user {
 	uint32_t ecctype;
 	uint32_t eccsize;
 	struct mtd_info *mtd;
+	uint32_t subpagesize;
 };
 
 struct region_info_user {
diff --git a/lib/libmtd.c b/lib/libmtd.c
index eecc76054..1606b872f 100644
--- a/lib/libmtd.c
+++ b/lib/libmtd.c
@@ -308,6 +308,7 @@ int mtd_get_dev_info(const char *node, struct mtd_dev_info *mtd)
 	mtd->eb_size = ui.erasesize;
 	mtd->min_io_size = ui.writesize;
 	mtd->oob_size = ui.oobsize;
+	mtd->subpage_size = ui.subpagesize;
 
 	if (mtd->min_io_size <= 0) {
 		errmsg("%s has insane min. I/O unit size %d",
@@ -356,7 +357,6 @@ int mtd_get_dev_info(const char *node, struct mtd_dev_info *mtd)
 
 	if (ui.flags & MTD_WRITEABLE)
 		mtd->writable = 1;
-	mtd->subpage_size = mtd->min_io_size;
 
 	close(fd);