diff --git a/plat/mediatek/mt8173/plat_pm.c b/plat/mediatek/mt8173/plat_pm.c
index e663b94..a84d031 100644
--- a/plat/mediatek/mt8173/plat_pm.c
+++ b/plat/mediatek/mt8173/plat_pm.c
@@ -497,8 +497,9 @@
 	/* Write the System Configuration Control Register */
 	INFO("MTK System Reset\n");
 
-	mmio_clrbits_32(MTK_WDT_BASE,
-		(MTK_WDT_MODE_DUAL_MODE | MTK_WDT_MODE_IRQ));
+	mmio_clrsetbits_32(MTK_WDT_BASE,
+		(MTK_WDT_MODE_DUAL_MODE | MTK_WDT_MODE_IRQ),
+		MTK_WDT_MODE_KEY);
 	mmio_setbits_32(MTK_WDT_BASE, (MTK_WDT_MODE_KEY | MTK_WDT_MODE_EXTEN));
 	mmio_setbits_32(MTK_WDT_SWRST, MTK_WDT_SWRST_KEY);