diff --git a/libretro/libretro.h b/libretro/libretro.h
index 6de87836..c6ac4c62 100755
--- a/libretro/libretro.h
+++ b/libretro/libretro.h
@@ -651,9 +651,14 @@ enum retro_mod
                                            // Can be called from retro_init and retro_load_game.
                                            //
 
-#define RETRO_MEMDESC_CONST     (1 << 0) // The frontend will never change this memory area once retro_load_game has returned.
-#define RETRO_MEMDESC_BIGENDIAN (1 << 1) // The memory area contains big endian data. Default is little endian.
-#define RETRO_MEMDESC_ALIGNED   (1 << 2) // All memory access in this area is aligned to their own size, and no non-power-of-two sized data exists.
+#define RETRO_MEMDESC_CONST     (1 << 0)  // The frontend will never change this memory area once retro_load_game has returned.
+#define RETRO_MEMDESC_BIGENDIAN (1 << 1)  // The memory area contains big endian data. Default is little endian.
+#define RETRO_MEMDESC_ALIGN_2   (1 << 16) // All memory access in this area is aligned to their own size, or 2, whichever is smaller.
+#define RETRO_MEMDESC_ALIGN_4   (2 << 16)
+#define RETRO_MEMDESC_ALIGN_8   (3 << 16)
+#define RETRO_MEMDESC_MINSIZE_2 (1 << 24) // All memory in this region is accessed at least 2 bytes at the time.
+#define RETRO_MEMDESC_MINSIZE_4 (2 << 24)
+#define RETRO_MEMDESC_MINSIZE_8 (3 << 24)
 struct retro_memory_descriptor {
    uint64_t flags;
 
diff --git a/memmap.cpp b/memmap.cpp
index ce8165d3..911c6182 100644
--- a/memmap.cpp
+++ b/memmap.cpp
@@ -3330,6 +3330,7 @@ void CMemory::Map_SA1LoROMMap (void)
 	desc.start=0x400000;
 	desc.select=0xC00000;
 	desc.disconnect=0xFE0000;
+	desc.len=0x20000;
 	S9xAppendMapping(&desc);
 #endif