diff --git a/sdk/xtdk/amd64/arfuncs.h b/sdk/xtdk/amd64/arfuncs.h
index 50ebe29..72a9d2c 100644
--- a/sdk/xtdk/amd64/arfuncs.h
+++ b/sdk/xtdk/amd64/arfuncs.h
@@ -24,6 +24,10 @@ XTCDECL
 BOOLEAN
 ArCpuId(IN OUT PCPUID_REGISTERS Registers);
 
+XTCDECL
+VOID
+ArEnableExtendedPhysicalAddressing(IN ULONG_PTR PageMap);
+
 XTCDECL
 VOID
 ArHalt(VOID);