diff --git a/Shared/ShmupWorld.cs b/Shared/ShmupWorld.cs
index 5997bca..e7d86d3 100644
--- a/Shared/ShmupWorld.cs
+++ b/Shared/ShmupWorld.cs
@@ -21,9 +21,9 @@ namespace SemiColinGames {
         Vector2 motion = Vector2.Multiply(input[0].Motion, modelTime * speed);
         Position = Vector2.Add(Position, motion);
         Position.X = Math.Max(Position.X, HalfSize.X);
-        Position.X = Math.Min(Position.X, worldBounds.Size.X - HalfSize.X);
+        Position.X = Math.Min(Position.X, worldBounds.Width - HalfSize.X);
         Position.Y = Math.Max(Position.Y, HalfSize.Y);
-        Position.Y = Math.Min(Position.Y, worldBounds.Size.Y - HalfSize.Y);
+        Position.Y = Math.Min(Position.Y, worldBounds.Height - HalfSize.Y);
 
         // Check whether we need to add new shots.
         shotCooldown -= modelTime;