diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 831ef83f6de1..c4a17d72d025 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -74,12 +74,17 @@ static int rwdt_init_timeout(struct watchdog_device *wdev)
 static int rwdt_start(struct watchdog_device *wdev)
 {
 	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+	u8 val;
 
 	pm_runtime_get_sync(wdev->parent);
 
-	rwdt_write(priv, 0, RWTCSRB);
-	rwdt_write(priv, priv->cks, RWTCSRA);
+	/* Stop the timer before we modify any register */
+	val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
+	rwdt_write(priv, val, RWTCSRA);
+
 	rwdt_init_timeout(wdev);
+	rwdt_write(priv, priv->cks, RWTCSRA);
+	rwdt_write(priv, 0, RWTCSRB);
 
 	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
 		cpu_relax();