diff --git a/sdk/xtdk/amd64/mmtypes.h b/sdk/xtdk/amd64/mmtypes.h
index c5313e6..f6c91c1 100644
--- a/sdk/xtdk/amd64/mmtypes.h
+++ b/sdk/xtdk/amd64/mmtypes.h
@@ -30,6 +30,7 @@
 #define MM_PDI_SHIFT                               21
 #define MM_PPI_SHIFT                               30
 #define MM_PXI_SHIFT                               39
+#define MM_LA57_SHIFT                              48
 
 /* Number of PTEs per page */
 #define MM_PTE_PER_PAGE                            512
diff --git a/xtldr/arch/amd64/memory.c b/xtldr/arch/amd64/memory.c
index df9215c..07e3c06 100644
--- a/xtldr/arch/amd64/memory.c
+++ b/xtldr/arch/amd64/memory.c
@@ -165,11 +165,11 @@ BlMapPage(IN PXTBL_PAGE_MAPPING PageMap,
     while(NumberOfPages > 0)
     {
         /* Calculate the indices in the various Page Tables from the virtual address */
-        Pml5Entry = (VirtualAddress & ((ULONGLONG)0x1FF << 48)) >> 48;
-        Pml4Entry = (VirtualAddress & ((ULONGLONG)0x1FF << 39)) >> 39;
-        Pml3Entry = (VirtualAddress & ((ULONGLONG)0x1FF << 30)) >> 30;
-        Pml2Entry = (VirtualAddress & ((ULONGLONG)0x1FF << 21)) >> 21;
-        Pml1Entry = (VirtualAddress & ((ULONGLONG)0x1FF << 12)) >> 12;
+        Pml5Entry = (VirtualAddress & ((ULONGLONG)0x1FF << MM_LA57_SHIFT)) >> MM_LA57_SHIFT;
+        Pml4Entry = (VirtualAddress & ((ULONGLONG)0x1FF << MM_PXI_SHIFT)) >> MM_PXI_SHIFT;
+        Pml3Entry = (VirtualAddress & ((ULONGLONG)0x1FF << MM_PPI_SHIFT)) >> MM_PPI_SHIFT;
+        Pml2Entry = (VirtualAddress & ((ULONGLONG)0x1FF << MM_PDI_SHIFT)) >> MM_PDI_SHIFT;
+        Pml1Entry = (VirtualAddress & ((ULONGLONG)0x1FF << MM_PTI_SHIFT)) >> MM_PTI_SHIFT;
 
         /* Check page map level */
         if(PageMap->PageMapLevel == 5)
@@ -262,7 +262,7 @@ BlpSelfMapPml(IN PXTBL_PAGE_MAPPING PageMap,
     else
     {
         /* Calculate PML index based on provided self map address */
-        PmlIndex = (SelfMapAddress >> 39) & 0x1FF;
+        PmlIndex = (SelfMapAddress >> MM_PXI_SHIFT) & 0x1FF;
 
         /* Add self-mapping for PML4 */
         ((PHARDWARE_PTE)PageMap->PtePointer)[PmlIndex].PageFrameNumber = (UINT_PTR)PageMap->PtePointer / EFI_PAGE_SIZE;
diff --git a/xtldr/arch/i686/memory.c b/xtldr/arch/i686/memory.c
index 83a0f27..d34c20a 100644
--- a/xtldr/arch/i686/memory.c
+++ b/xtldr/arch/i686/memory.c
@@ -260,10 +260,10 @@ BlpSelfMapPml(IN PXTBL_PAGE_MAPPING PageMap,
     if(PageMap->PageMapLevel == 3)
     {
         /* Calculate PML index based on provided self map address */
-        PmlIndex = (SelfMapAddress >> 21) & 0x1FF;
+        PmlIndex = (SelfMapAddress >> MM_PDI_SHIFT) & 0x1FF;
 
         /* Get Page Directory */
-        Pml = (PHARDWARE_PTE)(((PHARDWARE_PTE)PageMap->PtePointer)[SelfMapAddress >> 30].PageFrameNumber * EFI_PAGE_SIZE);
+        Pml = (PHARDWARE_PTE)(((PHARDWARE_PTE)PageMap->PtePointer)[SelfMapAddress >> MM_PPI_SHIFT].PageFrameNumber * EFI_PAGE_SIZE);
 
         /* Add self-mapping for PML3 (PAE enabled) */
         for(Index = 0; Index < 4; Index++)
@@ -276,7 +276,7 @@ BlpSelfMapPml(IN PXTBL_PAGE_MAPPING PageMap,
     else
     {
         /* Calculate PML index based on provided self map address */
-        PmlIndex = (SelfMapAddress >> 22);
+        PmlIndex = (SelfMapAddress >> MM_PDI_LEGACY_SHIFT);
 
         /* Add self-mapping for PML2 (PAE disabled) */
         ((PHARDWARE_LEGACY_PTE)PageMap->PtePointer)[PmlIndex].PageFrameNumber = (UINT_PTR)PageMap->PtePointer / EFI_PAGE_SIZE;