diff --git a/boot/xtldr/arch/i686/memory.cc b/boot/xtldr/arch/i686/memory.cc
index a6c65da..877a8ac 100644
--- a/boot/xtldr/arch/i686/memory.cc
+++ b/boot/xtldr/arch/i686/memory.cc
@@ -317,7 +317,7 @@ Memory::MapPage(IN PXTBL_PAGE_MAPPING PageMap,
                 IN ULONGLONG PhysicalAddress,
                 IN ULONGLONG NumberOfPages)
 {
-    SIZE_T PageFrameNumber;
+    ULONGLONG PageFrameNumber;
     PVOID Pml1, Pml2, Pml3;
     SIZE_T Pml1Entry, Pml2Entry, Pml3Entry;
     PHARDWARE_LEGACY_PTE LegacyPmlTable;