diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
index 6ad9df948711..b751f43d76ed 100644
--- a/drivers/watchdog/mtk_wdt.c
+++ b/drivers/watchdog/mtk_wdt.c
@@ -123,6 +123,7 @@ static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
 
 	reg = readl(wdt_base + WDT_MODE);
 	reg &= ~WDT_MODE_EN;
+	reg |= WDT_MODE_KEY;
 	iowrite32(reg, wdt_base + WDT_MODE);
 
 	return 0;