diff --git a/OpenRA.Game/Map/Map.cs b/OpenRA.Game/Map/Map.cs
index afc43fd302..5a5ce00b1d 100644
--- a/OpenRA.Game/Map/Map.cs
+++ b/OpenRA.Game/Map/Map.cs
@@ -786,7 +786,7 @@ namespace OpenRA
 		public WPos CenterOfSubCell(CPos cell, SubCell subCell)
 		{
 			var index = (int)subCell;
-			if (index >= 0 && index <= Grid.SubCellOffsets.Length)
+			if (index >= 0 && index < Grid.SubCellOffsets.Length)
 				return CenterOfCell(cell) + Grid.SubCellOffsets[index];
 			return CenterOfCell(cell);
 		}
diff --git a/OpenRA.Game/Map/MapGrid.cs b/OpenRA.Game/Map/MapGrid.cs
index a48cddc0ef..5e2c643c16 100644
--- a/OpenRA.Game/Map/MapGrid.cs
+++ b/OpenRA.Game/Map/MapGrid.cs
@@ -168,7 +168,11 @@ namespace OpenRA
 			if (subCell == SubCell.Invalid || subCell == SubCell.Any)
 				return WVec.Zero;
 
-			return SubCellOffsets[(int)subCell];
+			var index = (int)subCell;
+			if (index >= 0 && index < SubCellOffsets.Length)
+				return SubCellOffsets[index];
+
+			return WVec.Zero;
 		}
 	}
 }