diff --git a/OpenRA.Game/Map/CellLayer.cs b/OpenRA.Game/Map/CellLayer.cs
index 72c607fd2d..6f5112307e 100644
--- a/OpenRA.Game/Map/CellLayer.cs
+++ b/OpenRA.Game/Map/CellLayer.cs
@@ -19,6 +19,7 @@ namespace OpenRA
 	public class CellLayer<T> : IEnumerable<T>
 	{
 		public readonly Size Size;
+		readonly Rectangle bounds;
 		public readonly TileShape Shape;
 		public event Action<CPos> CellEntryChanged = null;
 
@@ -30,6 +31,7 @@ namespace OpenRA
 		public CellLayer(TileShape shape, Size size)
 		{
 			Size = size;
+			bounds = new Rectangle(0, 0, Size.Width, Size.Height);
 			Shape = shape;
 			entries = new T[size.Width * size.Height];
 		}
@@ -122,6 +124,11 @@ namespace OpenRA
 		{
 			return GetEnumerator();
 		}
+
+		public bool Contains(MPos uv)
+		{
+			return bounds.Contains(uv.U, uv.V);
+		}
 	}
 
 	// Helper functions
diff --git a/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs b/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
index fdd0fc1111..12b84a31be 100644
--- a/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
+++ b/OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs
@@ -258,7 +258,7 @@ namespace OpenRA.Mods.Common.Traits
 			foreach (var cell in cellsAndNeighborsDirty)
 			{
 				var uv = cell.ToMPos(map.TileShape);
-				if (!map.Contains(uv))
+				if (!tileInfos.Contains(uv))
 					continue;
 
 				var tileInfo = tileInfos[uv];