diff --git a/OpenRA.Mods.Common/Traits/World/TerrainGeometryOverlay.cs b/OpenRA.Mods.Common/Traits/World/TerrainGeometryOverlay.cs
index 16f9cd5c44..3ec425b1be 100644
--- a/OpenRA.Mods.Common/Traits/World/TerrainGeometryOverlay.cs
+++ b/OpenRA.Mods.Common/Traits/World/TerrainGeometryOverlay.cs
@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using OpenRA.Graphics;
 using OpenRA.Mods.Common.Commands;
@@ -57,6 +58,8 @@ namespace OpenRA.Mods.Common.Traits
 
 			var map = wr.World.Map;
 			var colors = wr.World.Map.Rules.TerrainInfo.HeightDebugColors;
+			var lastColor = colors.Length - 1;
+			var heightStep = map.Grid.TileScale / 2;
 			var mouseCell = wr.Viewport.ViewToWorld(Viewport.LastMousePos).ToMPos(wr.World.Map);
 
 			foreach (var uv in wr.Viewport.AllVisibleCells.CandidateMapCoords)
@@ -77,8 +80,8 @@ namespace OpenRA.Mods.Common.Traits
 						var j = (i + 1) % p.Length;
 						var start = pos + p[i];
 						var end = pos + p[j];
-						var startColor = colors[height + p[i].Z / 512];
-						var endColor = colors[height + p[j].Z / 512];
+						var startColor = colors[Math.Min(lastColor, height + p[i].Z / heightStep)];
+						var endColor = colors[Math.Min(lastColor, height + p[j].Z / heightStep)];
 						yield return new LineAnnotationRenderable(start, end, width, startColor, endColor);
 					}
 				}