1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/mtd/nand/r852.c b/drivers/mtd/nand/r852.c
index 325930db3f04..baea83f4dea8 100644
--- a/drivers/mtd/nand/r852.c
+++ b/drivers/mtd/nand/r852.c
@@ -245,7 +245,7 @@ static void r852_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
         }
 
         /* write DWORD chinks - faster */
-        while (len) {
+        while (len >= 4) {
                 reg = buf[0] | buf[1] << 8 | buf[2] << 16 | buf[3] << 24;
                 r852_write_reg_dword(dev, R852_DATALINE, reg);
                 buf += 4;
@@ -254,8 +254,10 @@ static void r852_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
         }
 
         /* write rest */
-        while (len)
+        while (len > 0) {
                 r852_write_reg(dev, R852_DATALINE, *buf++);
+                len--;
+        }
 }
 
 /*