diff --git a/MdeModulePkg/Core/RuntimeDxe/Runtime.c b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
index 2a54140873..de8f2bfce0 100644
--- a/MdeModulePkg/Core/RuntimeDxe/Runtime.c
+++ b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
@@ -365,7 +365,8 @@ RuntimeDriverSetVirtualAddressMap (
   //
   // mVirtualMap is only valid during SetVirtualAddressMap() call
   //
-  mVirtualMap = NULL;
+  mVirtualMap         = NULL;
+  mVirtualMapMaxIndex = 0;
 
   return EFI_SUCCESS;
 }