diff --git a/MdeModulePkg/Universal/PcatRealTimeClockRuntimeDxe/PcRtc.c b/MdeModulePkg/Universal/PcatRealTimeClockRuntimeDxe/PcRtc.c
index 5d52071a7b..4b1ced7439 100644
--- a/MdeModulePkg/Universal/PcatRealTimeClockRuntimeDxe/PcRtc.c
+++ b/MdeModulePkg/Universal/PcatRealTimeClockRuntimeDxe/PcRtc.c
@@ -888,6 +888,11 @@ DayValid (
   DayOfMonth[10] = 30;
   DayOfMonth[11] = 31;
 
+  //
+  // The validity of Time->Month field should be checked before
+  //
+  ASSERT (Time->Month >=1);
+  ASSERT (Time->Month <=12);
   if (Time->Day < 1 ||
       Time->Day > DayOfMonth[Time->Month - 1] ||
       (Time->Month == 2 && (!IsLeapYear (Time) && Time->Day > 28))
@@ -1048,6 +1053,12 @@ IsWithinOneDay (
 
   Adjacent = FALSE;
 
+  //
+  // The validity of Time->Month field should be checked before
+  //
+  ASSERT (From->Month >=1);
+  ASSERT (From->Month <=12);
+  
   if (From->Year == To->Year) {
     if (From->Month == To->Month) {
       if ((From->Day + 1) == To->Day) {
diff --git a/MdeModulePkg/Universal/Variable/Pei/Ipf/VariableWorker.c b/MdeModulePkg/Universal/Variable/Pei/Ipf/VariableWorker.c
index a5e0e550e3..17f152a0f1 100644
--- a/MdeModulePkg/Universal/Variable/Pei/Ipf/VariableWorker.c
+++ b/MdeModulePkg/Universal/Variable/Pei/Ipf/VariableWorker.c
@@ -49,7 +49,9 @@ VariableIndexTableUpdate (
   IN      VARIABLE_HEADER        *Variable
   )
 {
-  IndexTable->Index[IndexTable->Length++] = (UINT16) (((UINT32)(UINTN) Variable) >> 2);
+  if (IndexTable->Length < VARIABLE_INDEX_TABLE_VOLUME) {
+    IndexTable->Index[IndexTable->Length++] = (UINT16) (((UINT32)(UINTN) Variable) >> 2);
+  }
 
   return;
 }
diff --git a/MdeModulePkg/Universal/Variable/Pei/Variable.c b/MdeModulePkg/Universal/Variable/Pei/Variable.c
index 471b6a4749..f98d236443 100644
--- a/MdeModulePkg/Universal/Variable/Pei/Variable.c
+++ b/MdeModulePkg/Universal/Variable/Pei/Variable.c
@@ -443,10 +443,8 @@ FindVariable (
       //
       // Record Variable in VariableIndex HOB
       //
-      if (IndexTable->Length < VARIABLE_INDEX_TABLE_VOLUME) {
-        VariableIndexTableUpdate (IndexTable, Variable);
-      }
-
+      VariableIndexTableUpdate (IndexTable, Variable);
+      
       if (CompareWithValidVariable (Variable, VariableName, VendorGuid, PtrTrack) == EFI_SUCCESS) {
         return EFI_SUCCESS;
       }
diff --git a/MdeModulePkg/Universal/Variable/Pei/VariableWorker.c b/MdeModulePkg/Universal/Variable/Pei/VariableWorker.c
index f9c5daa452..a99bfa8c50 100644
--- a/MdeModulePkg/Universal/Variable/Pei/VariableWorker.c
+++ b/MdeModulePkg/Universal/Variable/Pei/VariableWorker.c
@@ -48,7 +48,9 @@ VariableIndexTableUpdate (
   IN      VARIABLE_HEADER        *Variable
   )
 {
-  IndexTable->Index[IndexTable->Length++] = (UINT16) (UINTN) Variable;
+  if (IndexTable->Length < VARIABLE_INDEX_TABLE_VOLUME) {
+    IndexTable->Index[IndexTable->Length++] = (UINT16) (UINTN) Variable;
+  }
 
   return;
 }