diff --git a/Makefile b/Makefile
index 36370df35..25acf880c 100644
--- a/Makefile
+++ b/Makefile
@@ -151,12 +151,12 @@ $(foreach obj, $(pokecrystal11_vc_obj), $(eval $(call DEP,$(obj),$(obj:11_vc.o=.
 endif
 
 
-pokecrystal_opt         = -Cjv -t PM_CRYSTAL -i BYTE -n 0 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
-pokecrystal11_opt       = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
-pokecrystal_au_opt      = -Cjv -t PM_CRYSTAL -i BYTU -n 0 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
-pokecrystal_debug_opt   = -Cjv -t PM_CRYSTAL -i BYTE -n 0 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
-pokecrystal11_debug_opt = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
-pokecrystal11_vc_opt    = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x10 -r 3 -p 0
+pokecrystal_opt         = -Cjv -t PM_CRYSTAL -i BYTE -n 0 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
+pokecrystal11_opt       = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
+pokecrystal_au_opt      = -Cjv -t PM_CRYSTAL -i BYTU -n 0 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
+pokecrystal_debug_opt   = -Cjv -t PM_CRYSTAL -i BYTE -n 0 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
+pokecrystal11_debug_opt = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
+pokecrystal11_vc_opt    = -Cjv -t PM_CRYSTAL -i BYTE -n 1 -k 01 -l 0x33 -m 0x1b -r 3 -p 0
 
 %.gbc: $$(%_obj) layout.link
 	$(RGBLINK) -n $*.sym -m $*.map -l layout.link -o $@ $(filter %.o,$^)
diff --git a/constants/hardware_constants.asm b/constants/hardware_constants.asm
index f662348e3..cf696d84e 100644
--- a/constants/hardware_constants.asm
+++ b/constants/hardware_constants.asm
@@ -37,6 +37,12 @@ DEF RTC_DH EQU $0c ; Upper 1 bit of Day Counter, Carry Bit, Halt Flag
                    ; Bit 6  Halt (0=Active, 1=Stop Timer)
                    ; Bit 7  Day Counter Carry Bit (1=Counter Overflow)
 
+; MBC5
+DEF MBC5SRamEnable EQU $0000
+DEF MBC5RomBankLo  EQU $2000
+DEF MBC5RomBankHi  EQU $3000
+DEF MBC5SRamBank   EQU $4000
+
 ; interrupt flags
 DEF VBLANK     EQU 0
 DEF LCD_STAT   EQU 1
diff --git a/home/audio.asm b/home/audio.asm
index 3d2c26019..e067e853f 100644
--- a/home/audio.asm
+++ b/home/audio.asm
@@ -10,13 +10,13 @@ InitSound::
 	push af
 	ld a, BANK(_InitSound)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	call _InitSound
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	pop af
 	pop bc
@@ -34,13 +34,13 @@ UpdateSound::
 	push af
 	ld a, BANK(_UpdateSound)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	call _UpdateSound
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	pop af
 	pop bc
@@ -51,14 +51,14 @@ UpdateSound::
 _LoadMusicByte::
 ; [wCurMusicByte] = [a:de]
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	ld a, [de]
 	ld [wCurMusicByte], a
 	ld a, BANK(LoadMusicByte)
 
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	ret
 
 PlayMusic::
@@ -73,7 +73,7 @@ PlayMusic::
 	push af
 	ld a, BANK(_PlayMusic) ; aka BANK(_InitSound)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	ld a, e
 	and a
@@ -88,7 +88,7 @@ PlayMusic::
 .end
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	pop af
 	pop bc
 	pop de
@@ -107,7 +107,7 @@ PlayMusic2::
 	push af
 	ld a, BANK(_PlayMusic)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	push de
 	ld de, MUSIC_NONE
@@ -118,7 +118,7 @@ PlayMusic2::
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	pop af
 	pop bc
@@ -140,7 +140,7 @@ PlayCry::
 	; Cries are stuck in one bank.
 	ld a, BANK(PokemonCries)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	ld hl, PokemonCries
 rept MON_CRY_LENGTH
@@ -163,13 +163,13 @@ endr
 
 	ld a, BANK(_PlayCry)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	call _PlayCry
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	pop af
 	pop bc
@@ -200,7 +200,7 @@ PlaySFX::
 	push af
 	ld a, BANK(_PlaySFX)
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	ld a, e
 	ld [wCurSFX], a
@@ -208,7 +208,7 @@ PlaySFX::
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 .done
 	pop af
diff --git a/home/battle.asm b/home/battle.asm
index 55bf3670e..fa92b89b5 100644
--- a/home/battle.asm
+++ b/home/battle.asm
@@ -145,7 +145,7 @@ FarCopyRadioText::
 	ld d, a
 	ld a, [hli]
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	ld a, e
 	ld l, a
 	ld a, d
@@ -155,7 +155,7 @@ FarCopyRadioText::
 	call CopyBytes
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	ret
 
 BattleTextbox::
diff --git a/home/header.asm b/home/header.asm
index 2e8c58949..d1078c454 100644
--- a/home/header.asm
+++ b/home/header.asm
@@ -11,7 +11,7 @@ FarCall::
 SECTION "rst10", ROM0[$0010]
 Bankswitch::
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	ret
 
 SECTION "rst18", ROM0[$0018]
diff --git a/home/init.asm b/home/init.asm
index 278719256..c01a036ca 100644
--- a/home/init.asm
+++ b/home/init.asm
@@ -141,7 +141,7 @@ Init::
 	ldh [hBGMapAddress], a
 
 	xor a ; SRAM_DISABLE
-	ld [MBC3SRamEnable], a
+	ld [MBC5SRamEnable], a
 
 	ldh a, [hCGB]
 	and a
diff --git a/home/sram.asm b/home/sram.asm
index 4a30257eb..c01d8dd74 100644
--- a/home/sram.asm
+++ b/home/sram.asm
@@ -25,16 +25,16 @@ endc
 	push af
 ; enable sram write
 	ld a, SRAM_ENABLE
-	ld [MBC3SRamEnable], a
+	ld [MBC5SRamEnable], a
 ; select sram bank
 	pop af
-	ld [MBC3SRamBank], a
+	ld [MBC5SRamBank], a
 	ret
 
 CloseSRAM::
 	push af
 	ld a, SRAM_DISABLE
 ; disable sram write
-	ld [MBC3SRamEnable], a
+	ld [MBC5SRamEnable], a
 	pop af
 	ret
diff --git a/home/text.asm b/home/text.asm
index 244528819..1567ca548 100644
--- a/home/text.asm
+++ b/home/text.asm
@@ -745,7 +745,7 @@ TextCommand_FAR::
 	ld a, [hli]
 
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 
 	push hl
 	ld h, d
@@ -755,7 +755,7 @@ TextCommand_FAR::
 
 	pop af
 	ldh [hROMBank], a
-	ld [MBC3RomBank], a
+	ld [MBC5RomBankLo], a
 	ret
 
 TextCommand_BCD::