diff --git a/gbdk-lib/libc/targets/sm83/gb/crt0.s b/gbdk-lib/libc/targets/sm83/gb/crt0.s
index bcada45b..1d587280 100644
--- a/gbdk-lib/libc/targets/sm83/gb/crt0.s
+++ b/gbdk-lib/libc/targets/sm83/gb/crt0.s
@@ -18,33 +18,34 @@
 
         .org    0x20            ; RST 0x20 == call HL
 .call_hl::
-        JP      (HL)
+        jp (hl)
 
         .org    0x28            ; zero up to 256 bytes in C pointed by HL
 .MemsetSmall::
-        LD      (HL+),A
-        DEC     C
-        JR      NZ,.MemsetSmall
+        ld (hl+), a
+        dec c
+        jr nz, .MemsetSmall
         ret
 
         .org    0x30            ; copy up to 256 bytes in C from DE to HL
 .MemcpySmall::
-        LD      A, (DE)
-        LD      (HL+), A
-        INC     DE
-        DEC     C
-        JR      NZ,.MemcpySmall
-        RET
+        ld a, (de)
+        ld (hl+), a
+        inc de
+        dec c
+        jr nz,.MemcpySmall
+        ret
 
 ;       .org    0x38            ; crash handler utilized by crash_handler.h
 
         ;; Hardware interrupt vectors
         .org    0x40            ; VBL
 .int_VBL:
-        PUSH    AF
-        PUSH    HL
-        LD      HL,#.int_0x40
-        JP      .int
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x40
 
 ;       .org    0x48            ; LCD
 
@@ -58,68 +59,65 @@
         ;; space for drawing.s bit table
 
         .org    0x80
-.int::
-        PUSH    BC
-        PUSH    DE
-1$:
-        LD      A,(HL+)
-        OR      (HL)
-        JR      Z,.int_tail
-        PUSH    HL
-        LD      A,(HL-)
-        LD      L,(HL)
-        LD      H,A
-        RST     0x20            ; .call_hl
-        POP     HL
-        INC     HL
-        JR      1$
+
 _wait_int_handler::
-        ADD     SP,#4
-.int_tail:
-        POP     DE
-        POP     BC
-        POP     HL
-
-        ;; we return at least at the beginning of mode 2
+        pop  de                 ; discard return address
+.int_wait_tail::
+        pop  de
+        pop  bc
+        pop  hl
         WAIT_STAT
+        pop  af
+        reti
 
-        POP     AF
-        RETI
+_nowait_int_handler::
+        pop  de                 ; discard return address
+.int_nowait_tail::
+        pop  de
+        pop  bc
+        pop  hl
+        pop  af
+        reti
+
+.int_call_chain::
+        .rept (.INT_CALL_CHAIN_SIZE * 3)
+                nop
+        .endm
+        jp .int_wait_tail
 
         ;; VBlank default interrupt routine
 __standard_VBL_handler::
 .std_vbl:
-        LD      HL,#.sys_time
-        INC     (HL)
-        JR      NZ,2$
-        INC     HL
-        INC     (HL)
+        ld hl,#.sys_time
+        inc (hl)
+        jr nz, 2$
+        inc hl
+        inc (hl)
 2$:
-        CALL    .refresh_OAM
+        ld a, #1
+        ldh (.vbl_done), a
+
+        jp  .refresh_OAM
 
-        LD      A, #1
-        LDH     (.vbl_done),A
-        RET
 
 _refresh_OAM::
         WAIT_STAT
-        LD      A, #>_shadow_OAM
-        JP      .refresh_OAM + (.refresh_OAM_DMA - .start_refresh_OAM)
+        ld a, #>_shadow_OAM
+        jp .refresh_OAM + (.refresh_OAM_DMA - .start_refresh_OAM)
 
 .clear_WRAM:
-        XOR     A
-        LD      BC, #l__DATA
-        LD      HL, #s__DATA
-        CALL    .memset_simple
+        xor a
+        ld bc, #l__DATA
+        ld hl, #s__DATA
+        call .memset_simple
 
-        LD      A, #>_shadow_OAM
-        LDH     (__shadow_OAM_base), A
-        LD      H, A
-        XOR     A
-        LD      L, A
-        LD      C, #(40 << 2)   ; 40 entries 4 bytes each
-        RST     0x28
-        RET
+        ld a, #>_shadow_OAM
+        ldh (__shadow_OAM_base), a
+        ld h, a
+        xor a
+        ld l, a
+        ld c, #(40 << 2)   ; 40 entries 4 bytes each
+        jp .MemsetSmall
 
         ;; Wait for VBL interrupt to be finished
 .wait_vbl_done::
@@ -142,27 +140,18 @@ _vsync::
 
         .org    .MODE_TABLE
         ;; Jump table for modes: 4 modes, 4 bytes each 16 bytes total
-        RET
+        ret
 
         ;; GameBoy Header
         .org    0x100
 .header:
-        JR      .code_start
+        jr .code_start
 
         ;; Nintendo logo
         .org    0x104
-        .byte   0xCE,0xED,0x66,0x66
-        .byte   0xCC,0x0D,0x00,0x0B
-        .byte   0x03,0x73,0x00,0x83
-        .byte   0x00,0x0C,0x00,0x0D
-        .byte   0x00,0x08,0x11,0x1F
-        .byte   0x88,0x89,0x00,0x0E
-        .byte   0xDC,0xCC,0x6E,0xE6
-        .byte   0xDD,0xDD,0xD9,0x99
-        .byte   0xBB,0xBB,0x67,0x63
-        .byte   0x6E,0x0E,0xEC,0xCC
-        .byte   0xDD,0xDC,0x99,0x9F
-        .byte   0xBB,0xB9,0x33,0x3E
+        .byte   0xCE,0xED,0x66,0x66,0xCC,0x0D,0x00,0x0B,0x03,0x73,0x00,0x83,0x00,0x0C,0x00,0x0D
+        .byte   0x00,0x08,0x11,0x1F,0x88,0x89,0x00,0x0E,0xDC,0xCC,0x6E,0xE6,0xDD,0xDD,0xD9,0x99
+        .byte   0xBB,0xBB,0x67,0x63,0x6E,0x0E,0xEC,0xCC,0xDD,0xDC,0x99,0x9F,0xBB,0xB9,0x33,0x3E
 
         ;; Title of the game
         .org    0x134
@@ -254,10 +243,6 @@ _reset::
         ;; Clear the OAM by calling refresh_OAM
         CALL    .refresh_OAM
 
-        ;; Install interrupt routines
-        LD      DE,#.std_vbl
-        CALL    .add_VBL
-
         ;; Standard color palettes
         LD      A,#0b11100100   ; Grey 3 = 11 (Black)
                                 ; Grey 2 = 10 (Dark grey)
@@ -273,22 +258,19 @@ _reset::
         LDH     (.LCDC),A
         XOR     A
         LDH     (.IF),A
-        LD      A,#.VBL_IFLAG   ; switch on VBlank interrupt only
-        LDH     (.IE),A
-
-        LDH     (__current_bank),A      ; current bank is 1 at startup
-
-        XOR     A
 
         LD      HL,#.sys_time
         LD      (HL+),A
         LD      (HL),A
 
-        LDH     (.NR52),A       ; Turn sound off
+        LDH     (.NR52),A               ; Turn sound off
+
+        INC     A
+        LDH     (__current_bank),A      ; current bank is 1 at startup
 
         CALL    gsinit
 
-        EI                      ; Enable interrupts
+        EI                              ; Enable interrupts
 
         ;; Call the main function
         CALL    _main
@@ -324,63 +306,55 @@ _set_interrupts::
         ;; falldown to .remove_int
 _remove_VBL::
 .remove_VBL::
-        LD      HL,#.int_0x40
-
+        ld hl, #.int_0x40
         ;; Remove interrupt DE from interrupt list HL if it exists
         ;; Abort if a 0000 is found (end of list)
 .remove_int::
 1$:
-        LD      A,(HL+)
-        LD      C,A
-        LD      A,(HL+)
-        LD      B,A
-        OR      C
-        RET     Z               ; No interrupt found
-
-        LD      A,E
-        CP      C
-        JR      NZ,1$
-        LD      A,D
-        CP      B
-        JR      NZ,1$
-
-        LD      B,H
-        LD      C,L
-        DEC     BC
-        DEC     BC
-
-        ;; Now do a memcpy from here until the end of the list
+        ld a, (hl+)
+        cp #0xcd
+        ret nz
+        ld a, (hl+)
+        cp e
+        jr nz, 2$
+        ld a, d
+        cp (hl)
+        jr z, 3$
 2$:
-        LD      A,(HL+)
-        LD      (BC),A
-        INC     BC
-        LD      D,A
-        LD      A,(HL+)
-        LD      (BC),A
-        INC     BC
-        OR      D
-        JR      NZ, 2$
-        RET
+        inc hl
+        jr 1$
+3$:
+        dec hl
+        dec hl
+        xor a
+        ld (hl+), a
+        ld (hl+), a
+        ld (hl+), a
+        ret
 
         ;; Add interrupt routine in DE to the VBL interrupt list
         ;; falldown to .add_int
 _add_VBL::
 .add_VBL::
-        LD      HL,#.int_0x40
-
+        ld hl, #.int_0x40
         ;; Add interrupt routine in DE to the interrupt list in HL
 .add_int::
+        ld bc, #3
 1$:
-        LD      A,(HL+)
-        OR      (HL)
-        JR      Z,2$
-        INC     HL
-        JR      1$
+        ld a, (hl)
+        or a
+        jr z, 2$
+        cp #0xcd
+        ret nz
+        add hl, bc
+        jr 1$
 2$:
-        LD      A,D
-        LD      (HL-),A
-        LD      (HL),E
-        RET
+        ld (hl), #0xcd          ; CALL instruction
+        inc hl
+        ld (hl), e
+        inc hl
+        ld (hl), d
+        ret
 
         ;; ****************************************
 
@@ -425,14 +399,14 @@ __is_GBA::
 _sys_time::
         .ds     0x02            ; System time in VBL units
 .int_0x40::
-        .blkw   0x06            ; 5 interrupt handlers: 1 built-in + 4 user-defined
+        .blkb   ((.INT_CALL_CHAIN_SIZE + 1) * 3)
 
 .end_crt_globals:
 
         .area   _HRAM (ABS)
 
         .org    0xFF90
-__current_bank::        ; Current bank
+__current_bank::                ; Current bank
         .ds     0x01
 .vbl_done:
         .ds     0x01            ; Is VBL interrupt finished?
@@ -441,14 +415,29 @@ __shadow_OAM_base::
 
         ;; Runtime library
         .area   _GSINIT
+
 gsinit::
+        ;; initialize and enable VBlank interrupts
+        ld de, #.int_call_chain
+        ld hl, #.int_0x40
+        ld c, #((.INT_CALL_CHAIN_SIZE + 1) * 3)
+        rst 0x30                ; memcpysmall
+
+        ;; install standard VBlank interrupt routine
+        ld de, #.std_vbl
+        call .add_VBL
+
+        ld a, #.VBL_IFLAG       ; switch on VBlank interrupt
+        ldh (.IE), a
+
         ;; initialize static storage variables
-        LD      BC, #l__INITIALIZER
-        LD      HL, #s__INITIALIZER
-        LD      DE, #s__INITIALIZED
-        call    .memcpy_simple
+        ld bc, #l__INITIALIZER
+        ld hl, #s__INITIALIZER
+        ld de, #s__INITIALIZED
+        call .memcpy_simple
 
         .area   _GSFINAL
+
         ret
 
         .area   _HOME
diff --git a/gbdk-lib/libc/targets/sm83/gb/global.s b/gbdk-lib/libc/targets/sm83/gb/global.s
index 5364b594..592231ab 100644
--- a/gbdk-lib/libc/targets/sm83/gb/global.s
+++ b/gbdk-lib/libc/targets/sm83/gb/global.s
@@ -456,6 +456,8 @@
 
         .globl  .wait_vbl_done
 
+        .INT_CALL_CHAIN_SIZE = 3
+
         ;; Interrupt routines
         .globl  .add_VBL
 ;       .globl  .add_LCD        ;; don't link LCD.o by default
diff --git a/gbdk-lib/libc/targets/sm83/joy.s b/gbdk-lib/libc/targets/sm83/joy.s
index 650b2b3d..e925c9c4 100644
--- a/gbdk-lib/libc/targets/sm83/joy.s
+++ b/gbdk-lib/libc/targets/sm83/joy.s
@@ -1,29 +1,37 @@
-	.include	"global.s"
+        .include "global.s"
 
-	.globl	.int
+        .module joypad_interrupts
 
-	.area	_HEADER_JOY (ABS)
+        .area	_HEADER_JOY (ABS)
 
-	.org	0x60		; JOY
+        .org	0x60        	; JOY
 .int_JOY:
-	PUSH	AF
-	PUSH	HL
-	LD	HL,#.int_0x60
-	JP	.int
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x60
 
-	.area	_HOME
+        .area   _GSINIT
+
+        ld de, #.int_call_chain
+        ld hl, #.int_0x60
+        ld c, #((.INT_CALL_CHAIN_SIZE + 1) * 3)
+        rst 0x30                ; memcpysmall
+
+        .area	_HOME
 
 _add_JOY::
 .add_JOY::
-	LD	HL,#.int_0x60
-	JP	.add_int
+        ld hl, #.int_0x60
+        jp .add_int
 
 _remove_JOY::
 .remove_JOY::
-	LD	HL,#.int_0x60
-	JP	.remove_int
+        ld hl, #.int_0x60
+        jp .remove_int
 
-	.area	_DATA
+        .area        _DATA
 
 .int_0x60::
-	.blkw	0x05
+        .blkb ((.INT_CALL_CHAIN_SIZE + 1) * 3)
\ No newline at end of file
diff --git a/gbdk-lib/libc/targets/sm83/lcd.s b/gbdk-lib/libc/targets/sm83/lcd.s
index 00cd712b..5dc69a0d 100644
--- a/gbdk-lib/libc/targets/sm83/lcd.s
+++ b/gbdk-lib/libc/targets/sm83/lcd.s
@@ -1,63 +1,37 @@
-	.include	"global.s"
+        .include "global.s"
 
+        .module lcd_interrupts
 
-	.area	_HEADER_LCD (ABS)
+        .area   _HEADER_LCD (ABS)
 
-	.org	0x48		; LCD
+        .org    0x48            ; LCD
 .int_LCD:
-	JP	.int_lcd_handler
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x48
 
-	.area	_HOME
+        .area   _GSINIT
 
-.int_lcd_handler:
-	PUSH	AF
-	PUSH	HL
-	PUSH	BC
-	PUSH	DE
-	LD	HL, #.int_0x48 + 0
-	PUSH    HL		; for stack compatibility with std handler only!
-	LD	A,(HL+)
-	LD      H,(HL)
-	LD	L,A
-	OR	H
-	JR 	Z, 1$
-	RST     0x20		; .call_hl
-	LD	HL, #.int_0x48 + 2
-	LD	A,(HL+)
-	LD      H,(HL)
-	LD	L,A
-	OR      H
-	JR      Z, 1$
-	RST     0x20		; .call_hl
-	LD	HL, #.int_0x48 + 4
-	LD	A,(HL+)
-	LD      H,(HL)
-	LD	L,A
-	OR      H
-	CALL    NZ, .call_hl
-1$:
-	POP     HL
-	POP	DE
-	POP	BC
-	POP	HL
+        ld de, #.int_call_chain
+        ld hl, #.int_0x48
+        ld c, #((.INT_CALL_CHAIN_SIZE + 1) * 3)
+        rst 0x30                ; memcpysmall
 
-	;; we return at least at the beginning of mode 2
-	WAIT_STAT
-
-	POP	AF
-	RETI
+        .area   _HOME
 
 _add_LCD::
 .add_LCD::
-	LD	HL,#.int_0x48
-	JP	.add_int
+        ld hl, #.int_0x48
+        jp .add_int
 
 _remove_LCD::
 .remove_LCD::
-	LD	HL,#.int_0x48
-	JP	.remove_int
+        ld hl, #.int_0x48
+        jp .remove_int
 
-	.area	_DATA
+        .area   _DATA
 
 .int_0x48::
-	.blkw	0x04
+        .blkb ((.INT_CALL_CHAIN_SIZE + 1) * 3)
\ No newline at end of file
diff --git a/gbdk-lib/libc/targets/sm83/serial.s b/gbdk-lib/libc/targets/sm83/serial.s
index f9ccbc32..87dcefa4 100644
--- a/gbdk-lib/libc/targets/sm83/serial.s
+++ b/gbdk-lib/libc/targets/sm83/serial.s
@@ -1,108 +1,109 @@
-	.include	"global.s"
+        .include "global.s"
 
-	.module serial
+        .module serial
 
-	.globl	.int
+        .globl	__io_out, __io_in, __io_status
+    	.globl	.add_SIO
 
-	.globl	__io_out
-	.globl	__io_in
-	.globl	__io_status
-    .globl	.add_SIO
+        .area	_HEADER_SIO (ABS)
 
-	.area	_HEADER_SIO (ABS)
+        .area	_GSINIT
 
-	.area	_GSINIT
+        ;; initialize SIO
+        ld de, #.int_call_chain
+        ld hl, #.int_0x58
+        ld c, #((.INT_CALL_CHAIN_SIZE + 1) * 3)
+        rst 0x30                ; memcpysmall
 
-	;; initialize SIO
-	LD	DE,#.serial_IO
-	CALL	.add_SIO
+        LD		DE,#.serial_IO
+        CALL	.add_SIO
 
-	XOR	A
-	LDH	(.IF),A
+        XOR     A
+        LDH     (.IF),A
 
-	LDH	A,(.IE)
-	OR	A,#0b00001000	; Serial I/O	=   On
-	LDH	(.IE),A
+        LDH     A,(.IE)
+        OR      A,#0b00001000        	; Serial I/O = On
+        LDH     (.IE),A
 
-	LDH	(.SC),A		; Use external clock
-	LD	A,#.DT_IDLE
-	LDH	(.SB),A		; Send IDLE byte
-	LD	A,#0x80
-	LDH	(.SC),A		; Use external clock
+        LDH     (.SC),A                 ; Use external clock
+        LD      A,#.DT_IDLE
+        LDH     (.SB),A                 ; Send IDLE byte
+        LD      A,#0x80
+        LDH     (.SC),A                 ; Use external clock
 
-	.area	_HOME
+        .area	_HOME
 
-	;; Serial interrupt
+        ;; Serial interrupt
 .serial_IO::
-	LD	A,(__io_status) ; Get status
+        LD		A,(__io_status) ; Get status
 
-	CP	#.IO_RECEIVING
-	JR	NZ, 1$
+        CP      #.IO_RECEIVING
+        JR      NZ, 1$
 
-	;; Receiving data
-	LDH	A,(.SB)		; Get data byte
-	LD	(__io_in),A	; Store it
+        ;; Receiving data
+        LDH     A,(.SB)              	; Get data byte
+        LD      (__io_in),A        		; Store it
 
 2$:
-	LD	A,#.IO_IDLE
+        LD      A,#.IO_IDLE
 3$:
-	LD	(__io_status),A ; Store status
+        LD      (__io_status),A 		; Store status
 
-	XOR	A
-	LDH	(.SC),A		; Use external clock
-	LD	A,#.DT_IDLE
-	LDH	(.SB),A		; Reply with IDLE byte
+        XOR     A
+        LDH     (.SC),A                	; Use external clock
+        LD      A,#.DT_IDLE
+        LDH     (.SB),A                	; Reply with IDLE byte
 4$:
-	LD	A,#0x80
-	LDH	(.SC),A		; Enable transfer with external clock
-	RET
+        LD      A,#0x80
+        LDH     (.SC),A                	; Enable transfer with external clock
+        RET
 
 1$:
-	CP	#.IO_SENDING
-	JR	NZ, 4$
+        CP      #.IO_SENDING
+        JR      NZ, 4$
 
-	;; Sending data
-	LDH	A,(.SB)		; Get data byte
-	CP	#.DT_RECEIVING
-	JR	Z, 2$
-	LD	A,#.IO_ERROR
-	JR	3$
+        ;; Sending data
+        LDH     A,(.SB)                	; Get data byte
+        CP      #.DT_RECEIVING
+        JR      Z, 2$
+        LD      A,#.IO_ERROR
+        JR      3$
 
-	.area	_DATA
+        .area	_DATA
 
 __io_out::
-	.ds	0x01		; Byte to send
+        .ds     0x01                	; Byte to send
 __io_in::
-	.ds	0x01		; Received byte
+        .ds     0x01                	; Received byte
 __io_status::
-	.ds	0x01		; Status of serial IO
+        .ds     0x01                	; Status of serial IO
 .int_0x58::
-	.blkw	0x05
+        .blkb 	((.INT_CALL_CHAIN_SIZE + 1) * 3)
 
-	.area	_CODE
+        .area	_CODE
 
-	;; Send byte in __io_out to the serial port
+        ;; Send byte in __io_out to the serial port
 .send_byte:
-_send_byte::			; Banked
-	LD	A,#.IO_SENDING
-	LD	(__io_status),A ; Store status
-	LD	A,#0x01
-	LDH	(.SC),A		; Use internal clock
-	LD	A,(__io_out)
-	LDH	(.SB),A		; Send data byte
-	LD	A,#0x81
-	LDH	(.SC),A		; Use internal clock
-	RET
+_send_byte::
+        LD      A,#.IO_SENDING
+        LD      (__io_status),A ; Store status
+        LD      A,#0x01
+        LDH     (.SC),A                	; Use internal clock
+        LD      A,(__io_out)
+        LDH     (.SB),A                	; Send data byte
+        LD      A,#0x81
+        LDH     (.SC),A                	; Use internal clock
+        RET
 
-	;; Receive byte from the serial port in __io_in
+        ;; Receive byte from the serial port in __io_in
 .receive_byte:
-_receive_byte::			; Banked
-	LD	A,#.IO_RECEIVING
-	LD	(__io_status),A ; Store status
-	XOR	A
-	LDH	(.SC),A		; Use external clock
-	LD	A,#.DT_RECEIVING
-	LDH	(.SB),A		; Send RECEIVING byte
-	LD	A,#0x80
-	LDH	(.SC),A		; Use external clock
-	RET
+_receive_byte::
+        LD      A,#.IO_RECEIVING
+        LD      (__io_status),A 		; Store status
+        XOR     A
+        LDH     (.SC),A                	; Use external clock
+        LD      A,#.DT_RECEIVING
+        LDH     (.SB),A                	; Send RECEIVING byte
+        LD      A,#0x80
+        LDH     (.SC),A                	; Use external clock
+        RET
diff --git a/gbdk-lib/libc/targets/sm83/sio.s b/gbdk-lib/libc/targets/sm83/sio.s
index fc21b280..8ffd3bb8 100644
--- a/gbdk-lib/libc/targets/sm83/sio.s
+++ b/gbdk-lib/libc/targets/sm83/sio.s
@@ -1,26 +1,25 @@
-	.include	"global.s"
+        .include "global.s"
 
-	.module sio
+        .module sio_interrupts
 
-	.globl	.int
+        .area    _HEADER_SIO (ABS)
 
-	.area	_HEADER_SIO (ABS)
-
-	.org	0x58		; SIO
+        .org    0x58        ; SIO
 .int_SIO:
-	PUSH	AF
-	PUSH	HL
-	LD	HL,#.int_0x58
-	JP	.int
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x58
 
-	.area	_HOME
+        .area    _HOME
 
 _add_SIO::
 .add_SIO::
-	LD	HL,#.int_0x58
-	JP	.add_int
+        ld hl, #.int_0x58
+        jp .add_int
 
 _remove_SIO::
 .remove_SIO::
-	LD	HL,#.int_0x58
-	JP	.remove_int
+        ld hl, #.int_0x58
+        jp .remove_int
diff --git a/gbdk-lib/libc/targets/sm83/tim.s b/gbdk-lib/libc/targets/sm83/tim.s
index d3b5ab32..50529270 100644
--- a/gbdk-lib/libc/targets/sm83/tim.s
+++ b/gbdk-lib/libc/targets/sm83/tim.s
@@ -1,18 +1,18 @@
-        .include        "global.s"
+        .include "global.s"
 
-        .globl  .int, .int_0x50
-        .globl  .add_TIM
+        .module timer_interrupts
 
         .area   _HEADER_TIM (ABS)
 
         .org    0x50            ; TIM
 .int_TIM:
-        PUSH    AF
-        PUSH    HL
-        LD      HL,#.int_0x50
-        JP      .int
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x50
 
         .area   _HOME
 
 _add_TIM::
-        JP      .add_TIM
+        jp .add_TIM
diff --git a/gbdk-lib/libc/targets/sm83/tim_common.s b/gbdk-lib/libc/targets/sm83/tim_common.s
index 011820c1..f98e34e7 100644
--- a/gbdk-lib/libc/targets/sm83/tim_common.s
+++ b/gbdk-lib/libc/targets/sm83/tim_common.s
@@ -1,19 +1,26 @@
-        .include        "global.s"
+        .include "global.s"
 
-        .globl  .int, .add_int, .remove_int
+        .module timer
+
+        .area   _GSINIT
+
+        ld de, #.int_call_chain
+        ld hl, #.int_0x50
+        ld c, #((.INT_CALL_CHAIN_SIZE + 1) * 3)
+        rst 0x30                ; memcpysmall
 
         .area   _HOME
 
 .add_TIM::
-        LD      HL,#.int_0x50
-        JP      .add_int
+        ld hl, #.int_0x50
+        jp .add_int
 
 _remove_TIM::
 .remove_TIM::
-        LD      HL,#.int_0x50
-        JP      .remove_int
+        ld hl, #.int_0x50
+        jp .remove_int
 
         .area   _DATA
 
 .int_0x50::
-        .blkw   0x05
+        .blkb ((.INT_CALL_CHAIN_SIZE + 1) * 3)
diff --git a/gbdk-lib/libc/targets/sm83/tim_nested.s b/gbdk-lib/libc/targets/sm83/tim_nested.s
index 19308556..9389a11c 100644
--- a/gbdk-lib/libc/targets/sm83/tim_nested.s
+++ b/gbdk-lib/libc/targets/sm83/tim_nested.s
@@ -1,22 +1,19 @@
         .include        "global.s"
 
-        .globl  .int, .int_0x50
-        .globl  .add_TIM
+        .module nested_timer_interrupts
 
         .area   _HEADER_NESTED_TIM (ABS)
 
         .org    0x50            ; TIM
 .int_TIM_nested:
-        EI
-        PUSH    AF
-        PUSH    HL
-        JP      .process_TIM_callbacks
+        ei
+        push af
+        push hl
+        push bc
+        push de
+        jp .int_0x50
 
         .area   _HOME
 
-.process_TIM_callbacks:
-        LD      HL, #.int_0x50
-        JP      .int
-
 _add_low_priority_TIM::
-         JP      .add_TIM
+        jp .add_TIM