diff --git a/OpenRA.Game/WorldUtils.cs b/OpenRA.Game/WorldUtils.cs
index eb5490e097..0e0b613690 100755
--- a/OpenRA.Game/WorldUtils.cs
+++ b/OpenRA.Game/WorldUtils.cs
@@ -124,6 +124,15 @@ namespace OpenRA
 				r.Next(w.Map.Bounds.Top, w.Map.Bounds.Bottom));
 		}
 
+		public static WPos FindMapEdge(this World w, WPos pos, WVec dir)
+		{
+			var tl = w.Map.Bounds.TopLeftAsCPos().TopLeft;
+			var br = w.Map.Bounds.BottomRightAsCPos().BottomRight;
+			var x = dir.X == 0 ? int.MaxValue : ((dir.X < 0 ? tl.X : br.X) - pos.X) / dir.X;
+			var y = dir.Y == 0 ? int.MaxValue : ((dir.Y < 0 ? tl.Y : br.Y) - pos.Y) / dir.Y;
+			return pos + Math.Min(x, y) * dir;
+		}
+
 		public static bool HasVoices(this Actor a)
 		{
 			var selectable = a.Info.Traits.GetOrDefault<SelectableInfo>();