diff --git a/OpenRA.Game/Traits/TraitsInterfaces.cs b/OpenRA.Game/Traits/TraitsInterfaces.cs
index 4d07e2d1e9..6bfef115f7 100644
--- a/OpenRA.Game/Traits/TraitsInterfaces.cs
+++ b/OpenRA.Game/Traits/TraitsInterfaces.cs
@@ -134,7 +134,9 @@ namespace OpenRA.Traits
 	[RequireExplicitImplementation]
 	public interface INotifyCreated { void Created(Actor self); }
 
+	[RequireExplicitImplementation]
 	public interface INotifyAddedToWorld { void AddedToWorld(Actor self); }
+	[RequireExplicitImplementation]
 	public interface INotifyRemovedFromWorld { void RemovedFromWorld(Actor self); }
 
 	[RequireExplicitImplementation]
diff --git a/OpenRA.Mods.Cnc/Traits/EnergyWall.cs b/OpenRA.Mods.Cnc/Traits/EnergyWall.cs
index b9e86c3ad7..b8eba1be63 100644
--- a/OpenRA.Mods.Cnc/Traits/EnergyWall.cs
+++ b/OpenRA.Mods.Cnc/Traits/EnergyWall.cs
@@ -103,7 +103,7 @@ namespace OpenRA.Mods.Cnc.Traits
 			return !active;
 		}
 
-		public override void AddedToWorld(Actor self)
+		protected override void AddedToWorld(Actor self)
 		{
 			base.AddedToWorld(self);
 			blockedPositions = info.Tiles(self.Location);
diff --git a/OpenRA.Mods.Cnc/Traits/Render/WithBuildingBib.cs b/OpenRA.Mods.Cnc/Traits/Render/WithBuildingBib.cs
index 616a738446..1aa80a6d57 100644
--- a/OpenRA.Mods.Cnc/Traits/Render/WithBuildingBib.cs
+++ b/OpenRA.Mods.Cnc/Traits/Render/WithBuildingBib.cs
@@ -88,7 +88,7 @@ namespace OpenRA.Mods.Cnc.Traits
 			bi = self.Info.TraitInfo<BuildingInfo>();
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			var rows = info.HasMinibib ? 1 : 2;
 			var width = bi.Dimensions.X;
@@ -119,7 +119,7 @@ namespace OpenRA.Mods.Cnc.Traits
 			}
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			foreach (var a in anims)
 				rs.Remove(a);
diff --git a/OpenRA.Mods.Common/Scripting/ScriptTriggers.cs b/OpenRA.Mods.Common/Scripting/ScriptTriggers.cs
index 685f50d9a0..ac7039abcc 100644
--- a/OpenRA.Mods.Common/Scripting/ScriptTriggers.cs
+++ b/OpenRA.Mods.Common/Scripting/ScriptTriggers.cs
@@ -322,7 +322,7 @@ namespace OpenRA.Mods.Common.Scripting
 			}
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			if (world.Disposing)
 				return;
@@ -341,7 +341,7 @@ namespace OpenRA.Mods.Common.Scripting
 			}
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			if (world.Disposing)
 				return;
diff --git a/OpenRA.Mods.Common/Traits/Buildings/Building.cs b/OpenRA.Mods.Common/Traits/Buildings/Building.cs
index 59515fc0c9..82170b2116 100644
--- a/OpenRA.Mods.Common/Traits/Buildings/Building.cs
+++ b/OpenRA.Mods.Common/Traits/Buildings/Building.cs
@@ -295,7 +295,12 @@ namespace OpenRA.Mods.Common.Traits
 				NotifyBuildingComplete(self);
 		}
 
-		public virtual void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
+		{
+			AddedToWorld(self);
+		}
+
+		protected virtual void AddedToWorld(Actor self)
 		{
 			if (Info.RemoveSmudgesOnBuild)
 				RemoveSmudges();
diff --git a/OpenRA.Mods.Common/Traits/Buildings/Gate.cs b/OpenRA.Mods.Common/Traits/Buildings/Gate.cs
index 8d88203e10..1806b4156f 100644
--- a/OpenRA.Mods.Common/Traits/Buildings/Gate.cs
+++ b/OpenRA.Mods.Common/Traits/Buildings/Gate.cs
@@ -114,7 +114,7 @@ namespace OpenRA.Mods.Common.Traits
 			return !self.IsDisabled() && BuildComplete && blocking.AppearsFriendlyTo(self);
 		}
 
-		public override void AddedToWorld(Actor self)
+		protected override void AddedToWorld(Actor self)
 		{
 			base.AddedToWorld(self);
 			blockedPositions = Info.Tiles(self.Location);
diff --git a/OpenRA.Mods.Common/Traits/Conditions/ProximityExternalCondition.cs b/OpenRA.Mods.Common/Traits/Conditions/ProximityExternalCondition.cs
index 6472ee513c..e4df55ab67 100644
--- a/OpenRA.Mods.Common/Traits/Conditions/ProximityExternalCondition.cs
+++ b/OpenRA.Mods.Common/Traits/Conditions/ProximityExternalCondition.cs
@@ -62,13 +62,13 @@ namespace OpenRA.Mods.Common.Traits
 			cachedVRange = WDist.Zero;
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			cachedPosition = self.CenterPosition;
 			proximityTrigger = self.World.ActorMap.AddProximityTrigger(cachedPosition, cachedRange, cachedVRange, ActorEntered, ActorExited);
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			self.World.ActorMap.RemoveProximityTrigger(proximityTrigger);
 		}
diff --git a/OpenRA.Mods.Common/Traits/Crates/Crate.cs b/OpenRA.Mods.Common/Traits/Crates/Crate.cs
index ceccaa8bd8..0619e6abb4 100644
--- a/OpenRA.Mods.Common/Traits/Crates/Crate.cs
+++ b/OpenRA.Mods.Common/Traits/Crates/Crate.cs
@@ -212,7 +212,7 @@ namespace OpenRA.Mods.Common.Traits
 			return self.IsAtGroundLevel() && crushClasses.Contains(info.CrushClass);
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			self.World.AddToMaps(self, this);
 
@@ -221,7 +221,7 @@ namespace OpenRA.Mods.Common.Traits
 				cs.IncrementCrates();
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			self.World.RemoveFromMaps(self, this);
 
diff --git a/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs b/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
index d11dad37fa..3e3992801c 100644
--- a/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
+++ b/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
@@ -52,7 +52,7 @@ namespace OpenRA.Mods.Common.Traits
 			health = self.Trait<Health>();
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			if (!Info.StartOnThreshold)
 				return;
diff --git a/OpenRA.Mods.Common/Traits/Husk.cs b/OpenRA.Mods.Common/Traits/Husk.cs
index 2d70ae6554..88e76624bb 100644
--- a/OpenRA.Mods.Common/Traits/Husk.cs
+++ b/OpenRA.Mods.Common/Traits/Husk.cs
@@ -118,12 +118,12 @@ namespace OpenRA.Mods.Common.Traits
 			self.World.UpdateMaps(self, this);
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			self.World.AddToMaps(self, this);
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			self.World.RemoveFromMaps(self, this);
 		}
diff --git a/OpenRA.Mods.Common/Traits/Immobile.cs b/OpenRA.Mods.Common/Traits/Immobile.cs
index e5f21044c2..95c327c922 100644
--- a/OpenRA.Mods.Common/Traits/Immobile.cs
+++ b/OpenRA.Mods.Common/Traits/Immobile.cs
@@ -52,7 +52,7 @@ namespace OpenRA.Mods.Common.Traits
 		public WPos CenterPosition { get { return position; } }
 		public IEnumerable<Pair<CPos, SubCell>> OccupiedCells() { return occupied; }
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			self.World.ActorMap.AddInfluence(self, this);
 			self.World.ActorMap.AddPosition(self, this);
@@ -61,7 +61,7 @@ namespace OpenRA.Mods.Common.Traits
 				self.World.ScreenMap.Add(self);
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			self.World.ActorMap.RemoveInfluence(self, this);
 			self.World.ActorMap.RemovePosition(self, this);
diff --git a/OpenRA.Mods.Common/Traits/Mobile.cs b/OpenRA.Mods.Common/Traits/Mobile.cs
index 3134b5043a..bb774fc69b 100644
--- a/OpenRA.Mods.Common/Traits/Mobile.cs
+++ b/OpenRA.Mods.Common/Traits/Mobile.cs
@@ -569,12 +569,12 @@ namespace OpenRA.Mods.Common.Traits
 			}
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			self.World.AddToMaps(self, this);
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			self.World.RemoveFromMaps(self, this);
 		}
diff --git a/OpenRA.Mods.Common/Traits/ParaDrop.cs b/OpenRA.Mods.Common/Traits/ParaDrop.cs
index 54732d3b74..1ba8046ede 100644
--- a/OpenRA.Mods.Common/Traits/ParaDrop.cs
+++ b/OpenRA.Mods.Common/Traits/ParaDrop.cs
@@ -96,7 +96,7 @@ namespace OpenRA.Mods.Common.Traits
 			return actorToDrop.Trait<IPositionable>().CanEnterCell(p);
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			OnRemovedFromWorld(self);
 		}
diff --git a/OpenRA.Mods.Common/Traits/Passenger.cs b/OpenRA.Mods.Common/Traits/Passenger.cs
index 5dfdf1b7ce..46dc0326a7 100644
--- a/OpenRA.Mods.Common/Traits/Passenger.cs
+++ b/OpenRA.Mods.Common/Traits/Passenger.cs
@@ -120,7 +120,8 @@ namespace OpenRA.Mods.Common.Traits
 			return true;
 		}
 
-		public void RemovedFromWorld(Actor self) { Unreserve(self); }
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self) { Unreserve(self); }
+
 		public void Unreserve(Actor self)
 		{
 			if (ReservedCargo == null)
diff --git a/OpenRA.Mods.Common/Traits/Power/Power.cs b/OpenRA.Mods.Common/Traits/Power/Power.cs
index aafd317f96..a5610e87ff 100644
--- a/OpenRA.Mods.Common/Traits/Power/Power.cs
+++ b/OpenRA.Mods.Common/Traits/Power/Power.cs
@@ -43,9 +43,11 @@ namespace OpenRA.Mods.Common.Traits
 
 		protected override void TraitEnabled(Actor self) { PlayerPower.UpdateActor(self); }
 		protected override void TraitDisabled(Actor self) { PlayerPower.UpdateActor(self); }
-		public void AddedToWorld(Actor self) { PlayerPower.UpdateActor(self); }
-		public void RemovedFromWorld(Actor self) { PlayerPower.RemoveActor(self); }
-		public void OnOwnerChanged(Actor self, Player oldOwner, Player newOwner)
+
+		void INotifyAddedToWorld.AddedToWorld(Actor self) { PlayerPower.UpdateActor(self); }
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self) { PlayerPower.RemoveActor(self); }
+
+		void INotifyOwnerChanged.OnOwnerChanged(Actor self, Player oldOwner, Player newOwner)
 		{
 			PlayerPower.RemoveActor(self);
 			PlayerPower = newOwner.PlayerActor.Trait<PowerManager>();
diff --git a/OpenRA.Mods.Common/Traits/Render/WithWallSpriteBody.cs b/OpenRA.Mods.Common/Traits/Render/WithWallSpriteBody.cs
index eb17f98b95..6410d18989 100644
--- a/OpenRA.Mods.Common/Traits/Render/WithWallSpriteBody.cs
+++ b/OpenRA.Mods.Common/Traits/Render/WithWallSpriteBody.cs
@@ -155,7 +155,7 @@ namespace OpenRA.Mods.Common.Traits.Render
 				aat.SetDirty();
 		}
 
-		public void RemovedFromWorld(Actor self)
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
 		{
 			UpdateNeighbours(self);
 		}
diff --git a/OpenRA.Mods.D2k/Traits/Buildings/LaysTerrain.cs b/OpenRA.Mods.D2k/Traits/Buildings/LaysTerrain.cs
index 1c96240fd7..0ebf4a47f9 100644
--- a/OpenRA.Mods.D2k/Traits/Buildings/LaysTerrain.cs
+++ b/OpenRA.Mods.D2k/Traits/Buildings/LaysTerrain.cs
@@ -49,7 +49,7 @@ namespace OpenRA.Mods.D2k.Traits
 			buildingInfo = self.Info.TraitInfo<BuildingInfo>();
 		}
 
-		public void AddedToWorld(Actor self)
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
 		{
 			var map = self.World.Map;