diff --git a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
index 2063a59732..382e9af6bf 100644
--- a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
+++ b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
@@ -159,7 +159,8 @@ FindCompatibleNodeReg (
   IN  FDT_CLIENT_PROTOCOL     *This,
   IN  CONST CHAR8             *CompatibleString,
   OUT CONST VOID              **Reg,
-  OUT UINT32                  *RegElemSize,
+  OUT UINTN                   *AddressCells,
+  OUT UINTN                   *SizeCells,
   OUT UINT32                  *RegSize
   )
 {
@@ -185,7 +186,8 @@ FindCompatibleNodeReg (
     return EFI_NOT_FOUND;
   }
 
-  *RegElemSize = 8;
+  *AddressCells = 2;
+  *SizeCells = 2;
 
   return EFI_SUCCESS;
 }
diff --git a/ArmVirtPkg/Include/Protocol/FdtClient.h b/ArmVirtPkg/Include/Protocol/FdtClient.h
index 79a8f3ce1b..b593c74414 100644
--- a/ArmVirtPkg/Include/Protocol/FdtClient.h
+++ b/ArmVirtPkg/Include/Protocol/FdtClient.h
@@ -80,7 +80,8 @@ EFI_STATUS
   IN  FDT_CLIENT_PROTOCOL     *This,
   IN  CONST CHAR8             *CompatibleString,
   OUT CONST VOID              **Reg,
-  OUT UINT32                  *RegElemSize,
+  OUT UINTN                   *AddressCells,
+  OUT UINTN                   *SizeCells,
   OUT UINT32                  *RegSize
   );
 
diff --git a/ArmVirtPkg/Library/ArmVirtGicArchLib/ArmVirtGicArchLib.c b/ArmVirtPkg/Library/ArmVirtGicArchLib/ArmVirtGicArchLib.c
index a1cd2da2d4..64afc4de6b 100644
--- a/ArmVirtPkg/Library/ArmVirtGicArchLib/ArmVirtGicArchLib.c
+++ b/ArmVirtPkg/Library/ArmVirtGicArchLib/ArmVirtGicArchLib.c
@@ -36,7 +36,8 @@ ArmVirtGicArchLibConstructor (
   UINT32                IccSre;
   FDT_CLIENT_PROTOCOL   *FdtClient;
   CONST UINT64          *Reg;
-  UINT32                RegElemSize, RegSize;
+  UINT32                RegSize;
+  UINTN                 AddressCells, SizeCells;
   UINTN                 GicRevision;
   EFI_STATUS            Status;
   UINT64                DistBase, CpuBase, RedistBase;
@@ -47,11 +48,13 @@ ArmVirtGicArchLibConstructor (
 
   GicRevision = 2;
   Status = FdtClient->FindCompatibleNodeReg (FdtClient, "arm,cortex-a15-gic",
-                        (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+                        (CONST VOID **)&Reg, &AddressCells, &SizeCells,
+                        &RegSize);
   if (Status == EFI_NOT_FOUND) {
     GicRevision = 3;
     Status = FdtClient->FindCompatibleNodeReg (FdtClient, "arm,gic-v3",
-                          (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+                          (CONST VOID **)&Reg, &AddressCells, &SizeCells,
+                          &RegSize);
   }
   if (EFI_ERROR (Status)) {
     return Status;
diff --git a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
index 377262563e..8ecbe3fb5f 100644
--- a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
+++ b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
@@ -122,7 +122,8 @@ QemuFwCfgInitialize (
   EFI_STATUS                    Status;
   FDT_CLIENT_PROTOCOL           *FdtClient;
   CONST UINT64                  *Reg;
-  UINT32                        RegElemSize, RegSize;
+  UINT32                        RegSize;
+  UINTN                         AddressCells, SizeCells;
   UINT64                        FwCfgSelectorAddress;
   UINT64                        FwCfgSelectorSize;
   UINT64                        FwCfgDataAddress;
@@ -135,7 +136,8 @@ QemuFwCfgInitialize (
   ASSERT_EFI_ERROR (Status);
 
   Status = FdtClient->FindCompatibleNodeReg (FdtClient, "qemu,fw-cfg-mmio",
-                         (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+                         (CONST VOID **)&Reg, &AddressCells, &SizeCells,
+                         &RegSize);
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_WARN,
       "%a: No 'qemu,fw-cfg-mmio' compatible DT node found (Status == %r)\n",
@@ -143,7 +145,8 @@ QemuFwCfgInitialize (
     return EFI_SUCCESS;
   }
 
-  ASSERT (RegElemSize == sizeof (UINT64));
+  ASSERT (AddressCells == 2);
+  ASSERT (SizeCells == 2);
   ASSERT (RegSize == 2 * sizeof (UINT64));
 
   FwCfgDataAddress     = SwapBytes64 (Reg[0]);
diff --git a/ArmVirtPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.c b/ArmVirtPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.c
index 37aea80628..203946f97b 100644
--- a/ArmVirtPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.c
+++ b/ArmVirtPkg/XenAcpiPlatformDxe/XenAcpiPlatformDxe.c
@@ -45,7 +45,8 @@ GetXenArmAcpiRsdp (
   EFI_STATUS                                     Status;
   FDT_CLIENT_PROTOCOL                            *FdtClient;
   CONST UINT64                                   *Reg;
-  UINT32                                         RegElemSize, RegSize;
+  UINT32                                         RegSize;
+  UINTN                                          AddressCells, SizeCells;
   UINT64                                         RegBase;
   UINT8                                          Sum;
 
@@ -59,13 +60,16 @@ GetXenArmAcpiRsdp (
   ASSERT_EFI_ERROR (Status);
 
   Status = FdtClient->FindCompatibleNodeReg (FdtClient, "xen,guest-acpi",
-                        (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+                        (CONST VOID **)&Reg, &AddressCells, &SizeCells,
+                        &RegSize);
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_WARN, "%a: No 'xen,guest-acpi' compatible DT node found\n",
       __FUNCTION__));
     return EFI_NOT_FOUND;
   }
 
+  ASSERT (AddressCells == 2);
+  ASSERT (SizeCells == 2);
   ASSERT (RegSize == 2 * sizeof (UINT64));
 
   RegBase = SwapBytes64(Reg[0]);
diff --git a/ArmVirtPkg/XenioFdtDxe/XenioFdtDxe.c b/ArmVirtPkg/XenioFdtDxe/XenioFdtDxe.c
index 4a88db3217..ae012a76f5 100644
--- a/ArmVirtPkg/XenioFdtDxe/XenioFdtDxe.c
+++ b/ArmVirtPkg/XenioFdtDxe/XenioFdtDxe.c
@@ -31,7 +31,8 @@ InitializeXenioFdtDxe (
   EFI_STATUS            Status;
   FDT_CLIENT_PROTOCOL   *FdtClient;
   CONST UINT64          *Reg;
-  UINT32                RegElemSize, RegSize;
+  UINT32                RegSize;
+  UINTN                 AddressCells, SizeCells;
   EFI_HANDLE            Handle;
   UINT64                RegBase;
 
@@ -40,14 +41,17 @@ InitializeXenioFdtDxe (
   ASSERT_EFI_ERROR (Status);
 
   Status = FdtClient->FindCompatibleNodeReg (FdtClient, "xen,xen",
-                        (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+                        (CONST VOID **)&Reg, &AddressCells, &SizeCells,
+                        &RegSize);
   if (EFI_ERROR (Status)) {
     DEBUG ((EFI_D_WARN, "%a: No 'xen,xen' compatible DT node found\n",
       __FUNCTION__));
     return EFI_UNSUPPORTED;
   }
 
-  ASSERT (RegSize == 16);
+  ASSERT (AddressCells == 2);
+  ASSERT (SizeCells == 2);
+  ASSERT (RegSize == 2 * sizeof (UINT64));
 
   //
   // Retrieve the reg base from this node and wire it up to the