diff --git a/Shared/Player.cs b/Shared/Player.cs
index 5a3d439..c3f702f 100644
--- a/Shared/Player.cs
+++ b/Shared/Player.cs
@@ -38,6 +38,15 @@ namespace SemiColinGames {
       return new Rectangle(position.X - spriteWidth, position.Y - 7, spriteWidth * 2, 26);
     }
 
+    private Aabb Box(Point position) {
+      return Box(position, 0);
+    }
+
+    private Aabb Box(Point position, int yOffset) {
+      return new Aabb(new Vector2(position.X, position.Y - 7 + 13 + yOffset),
+          new Vector2(spriteWidth, 13));
+    }
+
     public void Update(float modelTime, History<Input> input, Rectangle[] collisionTargets) {
       Point oldPosition = position;
       Vector2 movement = HandleInput(modelTime, input);
@@ -47,21 +56,26 @@ namespace SemiColinGames {
       Rectangle playerBbox = Bbox(position);
       bool standingOnGround = false;
 
+      // TODO: we shouldn't hardcode the tile sizes here.
+      Vector2 halfBoxSize = new Vector2(World.TileSize / 2, World.TileSize / 2);
       foreach (var rect in collisionTargets) {
+        Aabb rectBox = new Aabb(
+          new Vector2(rect.X + World.TileSize / 2, rect.Y + World.TileSize / 2), halfBoxSize);
+        Aabb playerBox = Box(position);
         playerBbox = Bbox(position);
 
         // first we check for left-right collisions...
-        if (playerBbox.Intersects(rect)) {
+        if (playerBox.Intersect(rectBox) != null) {
           if (oldBbox.Right <= rect.Left && playerBbox.Right > rect.Left) {
             position.X = rect.Left - spriteWidth;
           }
           if (oldBbox.Left >= rect.Right && playerBbox.Left < rect.Right) {
             position.X = rect.Right + spriteWidth;
           }
-          playerBbox = Bbox(position);
+          playerBox = Box(position);
         }
         // after fixing that, we check for hitting our head or hitting the ground.
-        if (playerBbox.Intersects(rect)) {
+        if (playerBox.Intersect(rectBox) != null) {
           if (oldPosition.Y > position.Y) {
             int diff = playerBbox.Top - rect.Bottom;
             position.Y -= diff;
@@ -72,8 +86,8 @@ namespace SemiColinGames {
             position.Y -= diff;
           }
         } else {
-          playerBbox.Height += 1;
-          if (playerBbox.Intersects(rect)) {
+          playerBox = Box(position, 1);
+          if (playerBox.Intersect(rectBox) != null) {
             standingOnGround = true;
             Debug.AddRect(rect, Color.Cyan);
           } else {