diff --git a/include/functions.h b/include/functions.h
index 65514ca8e0..4cfd6cfe28 100644
--- a/include/functions.h
+++ b/include/functions.h
@@ -2927,8 +2927,8 @@ s32 ShrinkWindow_GetPillarboxTarget(void);
 void ShrinkWindow_SetPillarboxMagnitude(s32 magnitude);
 s32 ShrinkWindow_GetPillarboxMagnitude(void);
 void ShrinkWindow_Init(void);
-void ShrinkWindow_Fini(void);
-void ShrinkWindow_Step(s32 framerateDivisor);
+void ShrinkWindow_Destroy(void);
+void ShrinkWindow_Update(s32 framerateDivisor);
 void ShrinkWindow_Draw(GraphicsContext* gfxCtx);
 // void func_80161180(void);
 // void func_8016119C(void);
diff --git a/spec b/spec
index 0faeb12290..a569dba5fa 100644
--- a/spec
+++ b/spec
@@ -581,7 +581,6 @@ beginseg
     include "build/src/code/z_player_call.o"
     include "build/data/code/z_player_call.bss.o"
     include "build/src/code/z_shrink_window.o"
-    include "build/data/code/z_shrink_window.bss.o"
     include "build/src/code/db_camera.o"
     include "build/data/code/db_camera.bss.o"
     include "build/data/code/code_801D0B50.data.o"
diff --git a/src/code/z_shrink_window.c b/src/code/z_shrink_window.c
index 3b2d861144..194ee50839 100644
--- a/src/code/z_shrink_window.c
+++ b/src/code/z_shrink_window.c
@@ -1,25 +1,121 @@
+/**
+ * File: z_shrink_window.c
+ * Description: Draws black top/bottom/side borders on the viewing window (e.g. Z-targeting, talking to NPC)
+ */
 #include "global.h"
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_SetLetterboxTarget.s")
+ShrinkWindowContext gShrinkWindowContext;
+ShrinkWindowContext* gShrinkWindowContextPtr;
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_GetLetterboxTarget.s")
+void ShrinkWindow_SetLetterboxTarget(s32 target) {
+    gShrinkWindowContextPtr->letterboxTarget = target;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_SetLetterboxMagnitude.s")
+s32 ShrinkWindow_GetLetterboxTarget(void) {
+    return gShrinkWindowContextPtr->letterboxTarget;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_GetLetterboxMagnitude.s")
+void ShrinkWindow_SetLetterboxMagnitude(s32 magnitude) {
+    gShrinkWindowContextPtr->letterboxMagnitude = magnitude;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_SetPillarboxTarget.s")
+s32 ShrinkWindow_GetLetterboxMagnitude(void) {
+    return gShrinkWindowContextPtr->letterboxMagnitude;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_GetPillarboxTarget.s")
+void ShrinkWindow_SetPillarboxTarget(s32 target) {
+    gShrinkWindowContextPtr->pillarboxTarget = target;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_SetPillarboxMagnitude.s")
+s32 ShrinkWindow_GetPillarboxTarget(void) {
+    return gShrinkWindowContextPtr->pillarboxTarget;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_GetPillarboxMagnitude.s")
+void ShrinkWindow_SetPillarboxMagnitude(s32 magnitude) {
+    gShrinkWindowContextPtr->pillarboxMagnitude = magnitude;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_Init.s")
+s32 ShrinkWindow_GetPillarboxMagnitude(void) {
+    return gShrinkWindowContextPtr->pillarboxMagnitude;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_Fini.s")
+void ShrinkWindow_Init(void) {
+    gShrinkWindowContextPtr = &gShrinkWindowContext;
+    bzero(gShrinkWindowContextPtr, sizeof(gShrinkWindowContext));
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_Step.s")
+void ShrinkWindow_Destroy(void) {
+    gShrinkWindowContextPtr = NULL;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/code/z_shrink_window/ShrinkWindow_Draw.s")
+void ShrinkWindow_Update(s32 framerateDivisor) {
+    s32 step = ((framerateDivisor == 3) ? 10 : 30 / framerateDivisor);
+    s32 nextMagnitude;
+
+    nextMagnitude = gShrinkWindowContextPtr->letterboxMagnitude;
+    Math_StepToIGet(&nextMagnitude, gShrinkWindowContextPtr->letterboxTarget, step);
+    gShrinkWindowContextPtr->letterboxMagnitude = nextMagnitude;
+
+    nextMagnitude = gShrinkWindowContextPtr->pillarboxMagnitude;
+    Math_StepToIGet(&nextMagnitude, gShrinkWindowContextPtr->pillarboxTarget, step);
+    gShrinkWindowContextPtr->pillarboxMagnitude = nextMagnitude;
+}
+
+void ShrinkWindow_Draw(GraphicsContext* gfxCtx) {
+    Gfx* gfx;
+    s8 letterboxMagnitude = gShrinkWindowContextPtr->letterboxMagnitude;
+    s8 pillarboxMagnitude = gShrinkWindowContextPtr->pillarboxMagnitude;
+
+    if (letterboxMagnitude > 0) {
+        OPEN_DISPS(gfxCtx);
+
+        gfx = OVERLAY_DISP;
+
+        gDPPipeSync(gfx++);
+        gDPSetCycleType(gfx++, G_CYC_FILL);
+        gDPSetRenderMode(gfx++, G_RM_NOOP, G_RM_NOOP2);
+        gDPSetFillColor(gfx++, (GPACK_RGBA5551(0, 0, 0, 1) << 16) | GPACK_RGBA5551(0, 0, 0, 1));
+        gDPFillRectangle(gfx++, 0, 0, gScreenWidth - 1, letterboxMagnitude - 1);
+        gDPFillRectangle(gfx++, 0, gScreenHeight - letterboxMagnitude, gScreenWidth - 1, gScreenHeight - 1);
+
+        gDPPipeSync(gfx++);
+        gDPSetCycleType(gfx++, G_CYC_1CYCLE);
+        gDPSetRenderMode(gfx++, G_RM_XLU_SURF, G_RM_XLU_SURF2);
+        gDPSetPrimColor(gfx++, 0, 0, 0, 0, 0, 0);
+        gDPFillRectangle(gfx++, 0, letterboxMagnitude, gScreenWidth, letterboxMagnitude + 1);
+        gDPFillRectangle(gfx++, 0, gScreenHeight - letterboxMagnitude - 1, gScreenWidth,
+                         gScreenHeight - letterboxMagnitude);
+
+        gDPPipeSync(gfx++);
+        OVERLAY_DISP = gfx++;
+
+        CLOSE_DISPS(gfxCtx);
+    }
+    if (pillarboxMagnitude > 0) {
+        OPEN_DISPS(gfxCtx);
+
+        gfx = OVERLAY_DISP;
+
+        gDPPipeSync(gfx++);
+        gDPSetCycleType(gfx++, G_CYC_FILL);
+        gDPSetRenderMode(gfx++, G_RM_NOOP, G_RM_NOOP2);
+        gDPSetFillColor(gfx++, (GPACK_RGBA5551(0, 0, 0, 1) << 16) | GPACK_RGBA5551(0, 0, 0, 1));
+
+        gDPFillRectangle(gfx++, 0, 0, pillarboxMagnitude - 1, gScreenHeight - 1);
+        gDPFillRectangle(gfx++, gScreenWidth - pillarboxMagnitude, 0, gScreenWidth - 1, gScreenHeight - 1);
+
+        gDPPipeSync(gfx++);
+        gDPSetCycleType(gfx++, G_CYC_1CYCLE);
+        gDPSetRenderMode(gfx++, G_RM_XLU_SURF, G_RM_XLU_SURF2);
+        gDPSetPrimColor(gfx++, 0, 0, 0, 0, 0, 0);
+
+        gDPFillRectangle(gfx++, pillarboxMagnitude, 0, pillarboxMagnitude + 2, gScreenHeight);
+        gDPFillRectangle(gfx++, gScreenWidth - pillarboxMagnitude - 2, 0, gScreenWidth - pillarboxMagnitude,
+                         gScreenHeight);
+
+        gDPPipeSync(gfx++);
+        OVERLAY_DISP = gfx++;
+
+        CLOSE_DISPS(gfxCtx);
+    }
+}
diff --git a/src/overlays/gamestates/ovl_daytelop/z_daytelop.c b/src/overlays/gamestates/ovl_daytelop/z_daytelop.c
index ba34c24482..d4c729d564 100644
--- a/src/overlays/gamestates/ovl_daytelop/z_daytelop.c
+++ b/src/overlays/gamestates/ovl_daytelop/z_daytelop.c
@@ -205,7 +205,7 @@ void Daytelop_Main(GameState* thisx) {
 }
 
 void Daytelop_Destroy(GameState* thisx) {
-    ShrinkWindow_Fini();
+    ShrinkWindow_Destroy();
 }
 
 void Daytelop_nop80815770(DaytelopContext* this) {
@@ -227,7 +227,7 @@ void Daytelop_Init(GameState* thisx) {
 
     Game_SetFramerateDivisor(thisx, 1);
     SysMatrix_StateAlloc(thisx);
-    ShrinkWindow_Fini();
+    ShrinkWindow_Destroy();
     View_Init(&this->view, thisx->gfxCtx);
     thisx->main = Daytelop_Main;
     thisx->destroy = Daytelop_Destroy;
diff --git a/src/overlays/gamestates/ovl_opening/z_opening.c b/src/overlays/gamestates/ovl_opening/z_opening.c
index b19955071a..f3279db4ed 100644
--- a/src/overlays/gamestates/ovl_opening/z_opening.c
+++ b/src/overlays/gamestates/ovl_opening/z_opening.c
@@ -43,7 +43,7 @@ void Opening_Main(GameState* thisx) {
 }
 
 void Opening_Destroy(GameState* thisx) {
-    ShrinkWindow_Fini();
+    ShrinkWindow_Destroy();
 }
 
 void Opening_Init(GameState* thisx) {
diff --git a/src/overlays/gamestates/ovl_select/z_select.c b/src/overlays/gamestates/ovl_select/z_select.c
index da6808725b..d58f7ac856 100644
--- a/src/overlays/gamestates/ovl_select/z_select.c
+++ b/src/overlays/gamestates/ovl_select/z_select.c
@@ -887,7 +887,7 @@ void Select_Main(GameState* thisx) {
 }
 
 void Select_Destroy(GameState* thisx) {
-    ShrinkWindow_Fini();
+    ShrinkWindow_Destroy();
 }
 
 void Select_Init(GameState* thisx) {
diff --git a/src/overlays/gamestates/ovl_title/z_title.c b/src/overlays/gamestates/ovl_title/z_title.c
index 83e3f487ad..c8027fcbe4 100644
--- a/src/overlays/gamestates/ovl_title/z_title.c
+++ b/src/overlays/gamestates/ovl_title/z_title.c
@@ -145,7 +145,7 @@ void Title_Destroy(GameState* thisx) {
     TitleContext* this = (TitleContext*)thisx;
 
     func_80146E40(&this->gameState, &this->sramCtx);
-    ShrinkWindow_Fini();
+    ShrinkWindow_Destroy();
     CIC6105_Nop80081828();
 }
 
diff --git a/tools/actorfixer.py b/tools/actorfixer.py
index 16100c9261..238c7f9c04 100755
--- a/tools/actorfixer.py
+++ b/tools/actorfixer.py
@@ -20,6 +20,8 @@ animdict ={
     "func_800F0568": "Audio_PlaySoundAtPosition",
     "func_8016970C": "Play_CameraSetAtEye",
     "func_800BBA88": "Enemy_StartFinishingBlow",
+    "ShrinkWindow_Step": "ShrinkWindow_Update",
+    "ShrinkWindow_Fini": "ShrinkWindow_Destroy",
     "func_801A89A8": "Audio_QueueSeqCmd",
 }
 
diff --git a/tools/disasm/functions.txt b/tools/disasm/functions.txt
index 558565b7dc..b64e05c56b 100644
--- a/tools/disasm/functions.txt
+++ b/tools/disasm/functions.txt
@@ -2901,8 +2901,8 @@
     0x80160C78:("ShrinkWindow_SetPillarboxMagnitude",),
     0x80160C8C:("ShrinkWindow_GetPillarboxMagnitude",),
     0x80160CA0:("ShrinkWindow_Init",),
-    0x80160CD4:("ShrinkWindow_Fini",),
-    0x80160CE4:("ShrinkWindow_Step",),
+    0x80160CD4:("ShrinkWindow_Destroy",),
+    0x80160CE4:("ShrinkWindow_Update",),
     0x80160D98:("ShrinkWindow_Draw",),
     0x80161180:("func_80161180",),
     0x8016119C:("func_8016119C",),