diff --git a/OpenRA.Mods.Common/Traits/Radar/RadarColorFromTerrain.cs b/OpenRA.Mods.Common/Traits/Radar/RadarColorFromTerrain.cs
index eea87b7057..4702bc9a1e 100644
--- a/OpenRA.Mods.Common/Traits/Radar/RadarColorFromTerrain.cs
+++ b/OpenRA.Mods.Common/Traits/Radar/RadarColorFromTerrain.cs
@@ -16,7 +16,7 @@ namespace OpenRA.Mods.Common.Traits.Radar
 {
 	public class RadarColorFromTerrainInfo : ITraitInfo
 	{
-		public readonly string Terrain;
+		[FieldLoader.Require] public readonly string Terrain;
 		public object Create(ActorInitializer init) { return new RadarColorFromTerrain(init.Self, Terrain); }
 	}