diff --git a/boot/freeldr/freeldr/include/mm.h b/boot/freeldr/freeldr/include/mm.h
index 2c934153674..23a9f8d02a4 100644
--- a/boot/freeldr/freeldr/include/mm.h
+++ b/boot/freeldr/freeldr/include/mm.h
@@ -68,7 +68,9 @@ typedef struct _FREELDR_MEMORY_DESCRIPTOR
 #define MM_PAGE_SIZE    4096
 #define MM_PAGE_MASK    0xFFF
 #define MM_PAGE_SHIFT    12
-#define MM_MAX_PAGE        0xFFFFFFFFF /* 36 bits for the PFN */
+//HACK: ReactOS AMD64 can't handle the full memory range yet CORE-20265
+//#define MM_MAX_PAGE        0xFFFFFFFFF /* 36 bits for the PFN */
+#define MM_MAX_PAGE        0x1FFFFF
 #define MM_MAX_PAGE_LOADER 0x3FFFF /* on x64 freeldr only maps 1 GB */
 
 #define MM_SIZE_TO_PAGES(a)  \