diff --git a/battle/magikarp_length.asm b/battle/magikarp_length.asm
new file mode 100644
index 000000000..7b2d5e386
--- /dev/null
+++ b/battle/magikarp_length.asm
@@ -0,0 +1,220 @@
+CalcMagikarpLength: ; fbbfc
+; Return Magikarp's length (in mm) in MagikarpLength (big endian)
+;
+; input:
+;   de: EnemyMonDVs
+;   bc: PlayerID
+
+; This function is needlessly convoluted, and poorly commented.
+; Reading is discouraged.
+
+; In short, it generates a value between 190 and 1786 using
+; a Magikarp's DVs and its trainer ID. This value is further
+; scrutinized in GetEnemyMon to make longer Magikarp even rarer.
+
+; This is done by calculating the value using operands from
+; a conversion lookup table.
+
+; Our index is calculated by xoring DVs with the trainer ID:
+
+; bc = rrc(rrc(dvs)) xor rrc(id)
+
+; if bc < $a:     MagikarpLength = c + 190
+; if bc >= $ff00: MagikarpLength = c + 1370
+; else:           MagikarpLength = z*100 + (bc-x)/y
+
+; X, Y, and Z depend on the value of b as follows:
+
+; if b = 0:        x =   310,  y =   2,  z =  3
+; if b = 1:        x =   710,  y =   4,  z =  4
+; if b = 2-9:      x =  2710,  y =  20,  z =  5
+; if b = 10-29:    x =  7710,  y =  50,  z =  6
+; if b = 30-68:    x = 17710,  y = 100,  z =  7
+; if b = 69-126:   x = 32710,  y = 150,  z =  8
+; if b = 127-185:  x = 47710,  y = 150,  z =  9
+; if b = 186-224:  x = 57710,  y = 100,  z = 10
+; if b = 225-243:  x = 62710,  y =  50,  z = 11
+; if b = 244-251:  x = 64710,  y =  20,  z = 12
+; if b = 252-253:  x = 65210,  y =   5,  z = 13
+; if b = 254:      x = 65410,  y =   2,  z = 14
+
+; These values represent arbitrary conversion points.
+
+
+; b = rrcrrc(atkdefdv) xor rrc(id[0])
+	
+; id
+	ld h, b
+	ld l, c
+	ld a, [hli]
+	ld b, a
+	ld c, [hl]
+	rrc b
+	rrc c
+	
+; dvs
+	ld a, [de]
+	inc de
+	rrca
+	rrca
+	xor b
+	ld b, a
+	
+; c = rrcrrc(spdspcdv) xor rrc(id[1])
+	
+	ld a, [de]
+	rrca
+	rrca
+	xor c
+	ld c, a
+	
+; if bc < $000a:
+	ld a, b
+	and a
+	jr nz, .loadtable
+	ld a, c
+	cp a, $a
+	jr nc, .loadtable
+	
+; de = hl = bc + $be
+	ld hl, $be
+	add hl, bc
+	ld d, h
+	ld e, l
+	jr .endtable
+	
+.loadtable
+	ld hl, .MagikarpLengthTable
+	ld a, $02
+	ld [$d265], a
+	
+.readtable
+	ld a, [hli]
+	ld e, a
+	ld a, [hli]
+	ld d, a
+	call .BLessThanD
+	jr nc, .advancetable
+	
+; c = bc / [hl]
+	call .BCMinusDE
+	ld a, b
+	ld [$ffb3], a
+	ld a, c
+	ld [$ffb4], a
+	ld a, [hl]
+	ld [$ffb7], a
+	ld b, $02
+	call Divide
+	ld a, [$ffb6]
+	ld c, a
+	
+; de = c + 100 * (2 + number of rows down the table)
+	xor a
+	ld [$ffb4], a
+	ld [$ffb5], a
+	ld a, $64
+	ld [$ffb6], a
+	ld a, [$d265]
+	ld [$ffb7], a
+	call Multiply
+	ld b, $00
+	ld a, [$ffb6]
+	add c
+	ld e, a
+	ld a, [$ffb5]
+	adc b
+	ld d, a
+	jr .endtable
+	
+.advancetable
+	inc hl ; align to next triplet
+	ld a, [$d265]
+	inc a
+	ld [$d265], a
+	cp a, $10
+	jr c, .readtable
+	
+	call .BCMinusDE
+	ld hl, $0640
+	add hl, bc
+	ld d, h
+	ld e, l
+	
+.endtable
+	ld h, d
+	ld l, e
+	add hl, hl
+	add hl, hl
+	add hl, de
+	add hl, hl ; hl = de * 10
+	
+	ld de, $ff02
+	ld a, $ff
+.loop
+	inc a
+	add hl, de ; - 254
+	jr c, .loop
+	
+	ld d, $00
+	
+; mod $0c
+.modloop
+	cp a, $0c
+	jr c, .done
+	sub a, $0c
+	inc d
+	jr .modloop
+	
+.done
+	ld e, a
+	ld hl, MagikarpLength
+	ld [hl], d
+	inc hl
+	ld [hl], e
+	ret
+; fbc9a
+
+.BLessThanD ; fbc9a
+; return carry if b < d
+	ld a, b
+	cp d
+	ret c
+	ret nc
+; fbc9e
+
+.CLessThanE ; fbc9e
+; unused
+	ld a, c
+	cp e
+	ret
+; fbca1
+
+.BCMinusDE ; fbca1
+; bc -= de
+	ld a, c
+	sub e
+	ld c, a
+	ld a, b
+	sbc d
+	ld b, a
+	ret
+; fbca8
+
+.MagikarpLengthTable ; fbca8
+;	     ????, divisor
+	dwb $006e, $01
+	dwb $0136, $02
+	dwb $02c6, $04
+	dwb $0a96, $14
+	dwb $1e1e, $32
+	dwb $452e, $64
+	dwb $7fc6, $96
+	dwb $ba5e, $96
+	dwb $e16e, $64
+	dwb $f4f6, $32
+	dwb $fcc6, $14
+	dwb $feba, $05
+	dwb $ff82, $02
+; fbccf
+
diff --git a/main.asm b/main.asm
index 6674f4c76..745b8819c 100644
--- a/main.asm
+++ b/main.asm
@@ -5761,7 +5761,7 @@ LoadEnemyMon: ; 3e8eb
 	callab CalcMagikarpLength
 	
 ; We're clear if the length is < 1536
-	ld a, [MagikarpLengthHi]
+	ld a, [MagikarpLength]
 	cp a, $06 ; $600 = 1536
 	jr nz, .CheckMagikarpArea
 	
@@ -5770,7 +5770,7 @@ LoadEnemyMon: ; 3e8eb
 	cp a, $0c ; / $100
 	jr c, .CheckMagikarpArea
 ; Try again if > 1614
-	ld a, [MagikarpLengthLo]
+	ld a, [MagikarpLength + 1]
 	cp a, $50
 	jr nc, .GenerateDVs
 	
@@ -5779,7 +5779,7 @@ LoadEnemyMon: ; 3e8eb
 	cp a, $32 ; / $100
 	jr c, .CheckMagikarpArea
 ; Try again if > 1598
-	ld a, [MagikarpLengthLo]
+	ld a, [MagikarpLength + 1]
 	cp a, $40
 	jr nc, .GenerateDVs
 	
@@ -5804,7 +5804,7 @@ LoadEnemyMon: ; 3e8eb
 	cp a, $64 ; / $100
 	jr c, .Happiness
 ; Floor at length 1024
-	ld a, [MagikarpLengthHi]
+	ld a, [MagikarpLength]
 	cp a, $04 ; $400 = 1024
 	jr c, .GenerateDVs ; try again
 	
@@ -12693,190 +12693,7 @@ INCBIN "gfx/misc/town_map.lz"
 
 INCBIN "baserom.gbc", $f8ea3, $fbbfc - $f8ea3
 
-CalcMagikarpLength: ; fbbfc
-; Stores Magikarp's length at $d1ea-$d1eb in big endian
-;
-; input:
-;   de: EnemyMonDVs
-;   bc: PlayerID
-; output:
-;   $d1ea-$d1eb: length
-;
-; does a whole bunch of arbitrary nonsense
-; cycles through a table of arbitrary values
-; http://web.archive.org/web/20110628181718/http://upokecenter.com/games/gs/guides/magikarp.php
-
-; b = rrcrrc(atkdefdv) xor rrc(pidhi)
-	ld h, b
-	ld l, c
-	ld a, [hli]
-	ld b, a
-	ld c, [hl] ; ld bc, [PlayerID]
-	rrc b
-	rrc c
-	ld a, [de]
-	inc de
-	rrca
-	rrca
-	xor b
-	ld b, a
-	
-; c = rrcrrc(spdspcdv) xor rrc(pidlo)
-	ld a, [de]
-	rrca
-	rrca
-	xor c
-	ld c, a
-	
-; if bc < $000a:
-	ld a, b
-	and a
-	jr nz, .loadtable
-	ld a, c
-	cp a, $0a
-	jr nc, .loadtable
-	
-; de = hl = bc + $be
-	ld hl, $00be
-	add hl, bc
-	ld d, h
-	ld e, l
-	jr .endtable
-	
-.loadtable
-	ld hl, .MagikarpLengthTable
-	ld a, $02
-	ld [$d265], a
-	
-.readtable
-	ld a, [hli]
-	ld e, a
-	ld a, [hli]
-	ld d, a
-	call .BLessThanD
-	jr nc, .advancetable
-	
-; c = bc / [hl]
-	call .BCMinusDE
-	ld a, b
-	ld [$ffb3], a
-	ld a, c
-	ld [$ffb4], a
-	ld a, [hl]
-	ld [$ffb7], a
-	ld b, $02
-	call Divide
-	ld a, [$ffb6]
-	ld c, a
-	
-; de = c + $64 * (2 + number of rows down the table)
-	xor a
-	ld [$ffb4], a
-	ld [$ffb5], a
-	ld a, $64
-	ld [$ffb6], a
-	ld a, [$d265]
-	ld [$ffb7], a
-	call Multiply
-	ld b, $00
-	ld a, [$ffb6]
-	add c
-	ld e, a
-	ld a, [$ffb5]
-	adc b
-	ld d, a
-	jr .endtable
-	
-.advancetable
-	inc hl ; align to next triplet
-	ld a, [$d265]
-	inc a
-	ld [$d265], a
-	cp a, $10
-	jr c, .readtable
-	
-	call .BCMinusDE
-	ld hl, $0640
-	add hl, bc
-	ld d, h
-	ld e, l
-	
-.endtable
-	ld h, d
-	ld l, e
-	add hl, hl
-	add hl, hl
-	add hl, de
-	add hl, hl ; hl = de * 10
-	
-	ld de, $ff02
-	ld a, $ff
-.loop
-	inc a
-	add hl, de ; - 254
-	jr c, .loop
-	
-	ld d, $00
-	
-; mod $0c
-.modloop
-	cp a, $0c
-	jr c, .done
-	sub a, $0c
-	inc d
-	jr .modloop
-	
-.done
-	ld e, a
-	ld hl, $d1ea
-	ld [hl], d
-	inc hl
-	ld [hl], e
-	ret
-; fbc9a
-
-.BLessThanD ; fbc9a
-; return carry if b < d
-	ld a, b
-	cp d
-	ret c
-	ret nc
-; fbc9e
-
-.CLessThanE ; fbc9e
-; unused
-	ld a, c
-	cp e
-	ret
-; fbca1
-
-.BCMinusDE ; fbca1
-; bc -= de
-	ld a, c
-	sub e
-	ld c, a
-	ld a, b
-	sbc d
-	ld b, a
-	ret
-; fbca8
-
-.MagikarpLengthTable ; fbca8
-;		????, divisor
-	dwb $006e, $01
-	dwb $0136, $02
-	dwb $02c6, $04
-	dwb $0a96, $14
-	dwb $1e1e, $32
-	dwb $452e, $64
-	dwb $7fc6, $96
-	dwb $ba5e, $96
-	dwb $e16e, $64
-	dwb $f4f6, $32
-	dwb $fcc6, $14
-	dwb $feba, $05
-	dwb $ff82, $02
-; fbccf
+INCLUDE "battle/magikarp_length.asm"
 
 INCBIN "baserom.gbc",$FBCCF,$fc000-$fbccf
 
diff --git a/wram.asm b/wram.asm
index 31b292a3e..f598a0aa2 100644
--- a/wram.asm
+++ b/wram.asm
@@ -837,11 +837,9 @@ TileSetPalettes: ; d1e6
 	ds 2
 
 Buffer1:
-MagikarpLength:
-MagikarpLengthHi: ; d1ea
+MagikarpLength: ; d1ea
 	ds 1
-Buffer2:
-MagikarpLengthLo: ; d1eb
+Buffer2: ; d1eb
 	ds 1
 
 SECTION "prng2",BSS[$d1fa]