diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
index 9ec309c6b9..5abb71c032 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
@@ -166,7 +166,8 @@ PcRtcInit (
   // Set RTC configuration after get original time
   // The value of bit AIE should be reserved.
   //
-  RtcWrite (RTC_ADDRESS_REGISTER_B, (UINT8)(RTC_INIT_REGISTER_B | (RegisterB.Data & BIT5)));
+  RegisterB.Data = RTC_INIT_REGISTER_B | (RegisterB.Data & BIT5);
+  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);
 
   //
   // Release RTC Lock.