diff --git a/OpenRA.Mods.Common/Traits/World/ActorMap.cs b/OpenRA.Mods.Common/Traits/World/ActorMap.cs
index d14c38908a..0611e93979 100644
--- a/OpenRA.Mods.Common/Traits/World/ActorMap.cs
+++ b/OpenRA.Mods.Common/Traits/World/ActorMap.cs
@@ -446,7 +446,10 @@ namespace OpenRA.Mods.Common.Traits
 			self.World.AddFrameEndTask(s =>
 			{
 				if (CellsUpdated != null)
+				{
 					CellsUpdated(updatedCells);
+					updatedCells.Clear();
+				}
 			});
 		}