diff --git a/OpenRA.Mods.RA/Harvester.cs b/OpenRA.Mods.RA/Harvester.cs
index 8f69105829..a1dfb5cbaf 100644
--- a/OpenRA.Mods.RA/Harvester.cs
+++ b/OpenRA.Mods.RA/Harvester.cs
@@ -85,7 +85,10 @@ namespace OpenRA.Mods.RA
 		}
 
 		public void Deliver(Actor self, Actor proc)
-		{
+		{
+			if (!proc.IsInWorld)
+				return;	// fail to deliver if there is no proc.
+
 			proc.Trait<IAcceptOre>().GiveOre(contents.Sum(kv => kv.Key.ValuePerUnit * kv.Value));
 			contents.Clear();
 		}