diff --git a/MdeModulePkg/Core/Dxe/SysCall/BootServices.c b/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
index 323cbb4ce3..c0b89ae0e6 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
+++ b/MdeModulePkg/Core/Dxe/SysCall/BootServices.c
@@ -643,7 +643,7 @@ CallBootService (
         gCpu->GetMemoryAttributes (gCpu, (EFI_PHYSICAL_ADDRESS)(UserRsp->Arguments[5] + sizeof (EFI_HANDLE *) - 1), &Attributes);
         ASSERT ((Attributes & EFI_MEMORY_USER) != 0);
 
-        PagesNumber = EFI_SIZE_TO_PAGES (Argument4 * sizeof (EFI_HANDLE *));
+        PagesNumber = (UINT32)EFI_SIZE_TO_PAGES (Argument4 * sizeof (EFI_HANDLE *));
 
         Status = CoreAllocatePages (
                    AllocateAnyPages,
diff --git a/MdeModulePkg/Core/Dxe/SysCall/SupportedProtocols.c b/MdeModulePkg/Core/Dxe/SysCall/SupportedProtocols.c
index 38f7d977cc..4ee53708bb 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/SupportedProtocols.c
+++ b/MdeModulePkg/Core/Dxe/SysCall/SupportedProtocols.c
@@ -78,8 +78,8 @@ GoToRing3 (
 }
 
 STATIC
-EFIAPI
 VOID *
+EFIAPI
 Ring3Copy (
   IN VOID    *Core,
   IN UINT32  Size
@@ -248,7 +248,7 @@ CoreFileRead (
   Ring3Buffer = NULL;
   Ring3Pages  = NULL;
 
-  PagesNumber = EFI_SIZE_TO_PAGES (sizeof (UINTN *) + *BufferSize);
+  PagesNumber = (UINT32)EFI_SIZE_TO_PAGES (sizeof (UINTN *) + *BufferSize);
 
   Status = CoreAllocatePages (
              AllocateAnyPages,
@@ -399,7 +399,7 @@ CoreFileGetInfo (
   Ring3InformationType = NULL;
   Ring3Pages           = NULL;
 
-  PagesNumber = EFI_SIZE_TO_PAGES (sizeof (UINTN *) + *BufferSize + sizeof (EFI_GUID));
+  PagesNumber = (UINT32)EFI_SIZE_TO_PAGES (sizeof (UINTN *) + *BufferSize + sizeof (EFI_GUID));
 
   Status = CoreAllocatePages (
              AllocateAnyPages,
@@ -550,7 +550,7 @@ CoreFileOpen (
   Ring3FileName  = NULL;
   Ring3Pages     = NULL;
 
-  PagesNumber = EFI_SIZE_TO_PAGES (sizeof (EFI_FILE_PROTOCOL *) + StrSize (FileName));
+  PagesNumber = (UINT32)EFI_SIZE_TO_PAGES (sizeof (EFI_FILE_PROTOCOL *) + StrSize (FileName));
 
   Status = CoreAllocatePages (
              AllocateAnyPages,