diff --git a/reactos/ntoskrnl/include/internal/amd64/mm.h b/reactos/ntoskrnl/include/internal/amd64/mm.h
index a1aeaf22c2a..1889c64209f 100644
--- a/reactos/ntoskrnl/include/internal/amd64/mm.h
+++ b/reactos/ntoskrnl/include/internal/amd64/mm.h
@@ -23,6 +23,8 @@
 #define MI_HIGHEST_SYSTEM_ADDRESS       (PVOID)0xFFFFFFFFFFFFFFFFULL
 #define MI_SYSTEM_CACHE_WS_START        (PVOID)0xFFFFF78000001000ULL // CHECKME
 
+#define MI_LOWEST_VAD_ADDRESS           (PVOID)0x000000007FF00000ULL
+
 /* Memory sizes */
 #define MI_MIN_PAGES_FOR_NONPAGED_POOL_TUNING ((255*1024*1024) >> PAGE_SHIFT)
 #define MI_MIN_PAGES_FOR_SYSPTE_TUNING         ((19*1024*1024) >> PAGE_SHIFT)