diff --git a/desmume/src/MMU.cpp b/desmume/src/MMU.cpp
index bd3a28aef..2cd59a203 100644
--- a/desmume/src/MMU.cpp
+++ b/desmume/src/MMU.cpp
@@ -172,7 +172,7 @@ u8 * MMU_struct::MMU_MEM[2][256] = {
 		/* 7X*/	DUP16(MMU.ARM9_OAM),
 		/* 8X*/	DUP16(NULL),
 		/* 9X*/	DUP16(NULL),
-		/* AX*/	DUP16(NULL),
+		/* AX*/	DUP16(MMU.UNUSED_RAM),
 		/* BX*/	DUP16(MMU.UNUSED_RAM),
 		/* CX*/	DUP16(MMU.UNUSED_RAM),
 		/* DX*/	DUP16(MMU.UNUSED_RAM),
@@ -193,7 +193,7 @@ u8 * MMU_struct::MMU_MEM[2][256] = {
 		/* 7X*/	DUP16(MMU.UNUSED_RAM),
 		/* 8X*/	DUP16(NULL),
 		/* 9X*/	DUP16(NULL),
-		/* AX*/	DUP16(NULL),
+		/* AX*/	DUP16(MMU.UNUSED_RAM),
 		/* BX*/	DUP16(MMU.UNUSED_RAM),
 		/* CX*/	DUP16(MMU.UNUSED_RAM),
 		/* DX*/	DUP16(MMU.UNUSED_RAM),
@@ -216,7 +216,7 @@ u32 MMU_struct::MMU_MASK[2][256] = {
 		/* 7X*/	DUP16(0x000007FF),
 		/* 8X*/	DUP16(0x00000003),
 		/* 9X*/	DUP16(0x00000003),
-		/* AX*/	DUP16(0x0000FFFF),
+		/* AX*/	DUP16(0x00000003),
 		/* BX*/	DUP16(0x00000003),
 		/* CX*/	DUP16(0x00000003),
 		/* DX*/	DUP16(0x00000003),
@@ -237,7 +237,7 @@ u32 MMU_struct::MMU_MASK[2][256] = {
 		/* 7X*/	DUP16(0x00000003),
 		/* 8X*/	DUP16(0x00000003),
 		/* 9X*/	DUP16(0x00000003),
-		/* AX*/	DUP16(0x0000FFFF),
+		/* AX*/	DUP16(0x00000003),
 		/* BX*/	DUP16(0x00000003),
 		/* CX*/	DUP16(0x00000003),
 		/* DX*/	DUP16(0x00000003),