diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index 1bf192f229d7..74f89333a03e 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -154,6 +154,7 @@ static int register_device(struct platform_device *pdev, const char *name,
 	new->mtd.type = MTD_RAM;
 	new->mtd.erasesize = erasesize;
 	new->mtd.writesize = 1;
+	new->mtd.writebufsize = 1;
 
 	mtd_set_of_node(&new->mtd, np);