diff --git a/include/collision.h b/include/collision.h
new file mode 100644
index 00000000..d64492c1
--- /dev/null
+++ b/include/collision.h
@@ -0,0 +1,35 @@
+
+#ifndef COLLISION_H
+#define COLLISION_H
+
+#include "global.h"
+#include "entity.h"
+
+
+
+/** Collisions. */
+typedef enum {
+    COL_NONE = 0x0,
+    COL_NORTH_WEST = 0x2,
+    COL_NORTH_EAST = 0x4,
+    COL_NORTH_FULL = 0x6,
+    COL_NORTH_ANY = 0xe,
+    COL_SOUTH_WEST = 0x20,
+    COL_SOUTH_EAST = 0x40,
+    COL_SOUTH_FULL = 0x60,
+    COL_SOUTH_ANY = 0xe0,
+    COL_WEST_SOUTH = 0x200,
+    COL_WEST_NORTH = 0x400,
+    COL_WEST_FULL = 0x600,
+    COL_WEST_ANY = 0xe00,
+    COL_EAST_SOUTH = 0x2000,
+    COL_EAST_NORTH = 0x4000,
+    COL_EAST_FULL = 0x6000,
+    COL_EAST_ANY = 0xe000,
+} Collisions;
+
+bool32 IsTileCollision(const u8*, s32, s32, u32);
+void CalculateEntityTileCollisions(Entity*, u32, u32);
+bool32 ProcessMovementInternal(Entity*, s32, s32, u32);
+
+#endif
diff --git a/src/enemy/flyingPot.c b/src/enemy/flyingPot.c
index abba834c..1736979d 100644
--- a/src/enemy/flyingPot.c
+++ b/src/enemy/flyingPot.c
@@ -5,6 +5,7 @@
  * @brief Flying pot enemy
  */
 #define NENT_DEPRECATED
+#include "collision.h"
 #include "functions.h"
 #include "enemy.h"
 #include "player.h"
@@ -234,7 +235,7 @@ void FlyingPot_Action4(FlyingPotEntity* this) {
 void FlyingPot_Action5(FlyingPotEntity* this) {
     ProcessMovement2(super);
 
-    if (super->collisions != 0) {
+    if (super->collisions != COL_NONE) {
         sub_08037408(this);
     }
 }
diff --git a/src/movement.c b/src/movement.c
index 8fee2b1f..4674653e 100644
--- a/src/movement.c
+++ b/src/movement.c
@@ -1,4 +1,5 @@
 #include "global.h"
+#include "collision.h"
 #include "entity.h"
 #include "room.h"
 #include "area.h"
@@ -9,30 +10,6 @@
 #include "transitions.h"
 #include "functions.h"
 
-/** Collisions. */
-typedef enum {
-    COL_NONE = 0x0,
-    COL_NORTH_WEST = 0x2,
-    COL_NORTH_EAST = 0x4,
-    COL_NORTH_FULL = 0x6,
-    COL_NORTH_ANY = 0xe,
-    COL_SOUTH_WEST = 0x20,
-    COL_SOUTH_EAST = 0x40,
-    COL_SOUTH_FULL = 0x60,
-    COL_SOUTH_ANY = 0xe0,
-    COL_WEST_SOUTH = 0x200,
-    COL_WEST_NORTH = 0x400,
-    COL_WEST_FULL = 0x600,
-    COL_WEST_ANY = 0xe00,
-    COL_EAST_SOUTH = 0x2000,
-    COL_EAST_NORTH = 0x4000,
-    COL_EAST_FULL = 0x6000,
-    COL_EAST_ANY = 0xe000,
-} Collisions;
-
-bool32 IsTileCollision(const u8*, s32, s32, u32);
-void CalculateEntityTileCollisions(Entity*, u32, u32);
-bool32 ProcessMovementInternal(Entity*, s32, s32, u32);
 bool32 sub_080AF0C8(Entity*);
 
 /** The type of the movement/collision? that is done. */
diff --git a/src/projectile/winder.c b/src/projectile/winder.c
index 0c9fa318..bc7647f1 100644
--- a/src/projectile/winder.c
+++ b/src/projectile/winder.c
@@ -1,4 +1,5 @@
 #define NENT_DEPRECATED
+#include "collision.h"
 #include "entity.h"
 #include "asm.h"
 #include "functions.h"
@@ -6,15 +7,8 @@
 #include "projectile.h"
 #include "projectile/winder.h"
 
-// #define WINDER_NUM_SEGMENTS 8
-
 extern s16 gUnk_080B4488[];
 
-// typedef struct {
-//     Entity base;
-//     u16 positions[2 * WINDER_NUM_SEGMENTS];
-// } WinderEntity;
-
 typedef enum {
     /* 0 */ WINDER_TYPE_HEAD,
     /* 4 */ WINDER_TYPE_4 = 4,
@@ -24,7 +18,7 @@ void Winder_Init(WinderEntity* this);
 void sub_080AB950(WinderEntity* this);
 
 void Winder_SetPositions(WinderEntity*);
-bool32 sub_080AB9FC(WinderEntity* this, u32 dir);
+bool32 Winder_CheckNextTileCollision(WinderEntity* this, u32 dir);
 
 void Winder(Entity* thisx) {
     static void (*const Winder_Actions[])(WinderEntity*) = {
@@ -72,7 +66,7 @@ void sub_080AB950(WinderEntity* this) {
         { DirectionEast, DirectionWest },
         { DirectionNorth, DirectionSouth },
     };
-    static const u16 gUnk_0812A6C4[] = { 0x000E, 0xE000, 0x00E0, 0x0E00 };
+    static const u16 collisionChecks[] = { COL_NORTH_ANY, COL_EAST_ANY, COL_SOUTH_ANY, COL_WEST_ANY };
 
     if (super->type == 0) {
         u8 dir;
@@ -80,7 +74,7 @@ void sub_080AB950(WinderEntity* this) {
         ProcessMovement0(super);
 
         dir = super->direction >> 3;
-        if ((gUnk_0812A6C4[dir] & super->collisions) || sub_080AB9FC(this, super->direction)) {
+        if ((collisionChecks[dir] & super->collisions) || Winder_CheckNextTileCollision(this, super->direction)) {
             super->direction = nextDirections[dir][Random() & 0x1];
         }
     } else {
@@ -117,21 +111,21 @@ void Winder_SetPositions(WinderEntity* this) {
     this->positions[2 * (WINDER_NUM_SEGMENTS - 1) + 1] = super->y.HALF.HI;
 }
 
-bool32 sub_080AB9FC(WinderEntity* this, u32 dir) {
+bool32 Winder_CheckNextTileCollision(WinderEntity* this, u32 dir) {
+    u32 tile;
     u32 val;
     LayerStruct* layer = GetLayerByIndex(super->collisionLayer);
-    u32 tmp;
+    u32 collisionData;
 
-    val = (((super->x.HALF.HI - gRoomControls.origin_x) >> 4) & 0x3F) |
-          ((((super->y.HALF.HI - gRoomControls.origin_y) >> 4) & 0x3F) << 6);
-    val += gUnk_080B4488[dir >> 3];
-    tmp = layer->collisionData[val];
+    tile = TILE(super->x.HALF.HI, super->y.HALF.HI);
+    tile += gUnk_080B4488[dir >> 3];
+    collisionData = layer->collisionData[tile];
 
-    if (tmp <= 0x1F) {
+    if (collisionData <= 0x1F) {
         return FALSE;
     }
 
-    if (tmp > 0x3F) {
+    if (collisionData > 0x3F) {
         return FALSE;
     }