diff --git a/OpenRA.Game/GameRules/Warhead.cs b/OpenRA.Game/GameRules/Warhead.cs
index f34c88329e..9bdd950ace 100644
--- a/OpenRA.Game/GameRules/Warhead.cs
+++ b/OpenRA.Game/GameRules/Warhead.cs
@@ -29,7 +29,7 @@ namespace OpenRA.GameRules
 
 		public abstract void DoImpact(Target target, Actor firedBy, float firepowerModifier);
 
-		public abstract float EffectivenessAgainst(ActorInfo ai);
+		public virtual float EffectivenessAgainst(ActorInfo ai) { return 0f; }
 
 		public bool IsValidAgainst(Target target, World world, Actor firedBy)
 		{
diff --git a/OpenRA.Mods.RA/Warheads/CreateEffectWarhead.cs b/OpenRA.Mods.RA/Warheads/CreateEffectWarhead.cs
index b966f11125..7fe28579de 100644
--- a/OpenRA.Mods.RA/Warheads/CreateEffectWarhead.cs
+++ b/OpenRA.Mods.RA/Warheads/CreateEffectWarhead.cs
@@ -95,8 +95,6 @@ namespace OpenRA.Mods.RA
 				Sound.Play(ImpactSound, pos);
 		}
 
-		public override float EffectivenessAgainst(ActorInfo ai) { return 1f; }
-
 		public bool IsValidImpact(WPos pos, Actor firedBy)
 		{
 			var world = firedBy.World;
diff --git a/OpenRA.Mods.RA/Warheads/CreateResourceWarhead.cs b/OpenRA.Mods.RA/Warheads/CreateResourceWarhead.cs
index 8164f9cb1c..86743323ce 100644
--- a/OpenRA.Mods.RA/Warheads/CreateResourceWarhead.cs
+++ b/OpenRA.Mods.RA/Warheads/CreateResourceWarhead.cs
@@ -60,7 +60,5 @@ namespace OpenRA.Mods.RA
 				}
 			}
 		}
-
-		public override float EffectivenessAgainst(ActorInfo ai) { return 1f; }
 	}
 }
diff --git a/OpenRA.Mods.RA/Warheads/DestroyResourceWarhead.cs b/OpenRA.Mods.RA/Warheads/DestroyResourceWarhead.cs
index 3a21458e4b..4bde5a3693 100644
--- a/OpenRA.Mods.RA/Warheads/DestroyResourceWarhead.cs
+++ b/OpenRA.Mods.RA/Warheads/DestroyResourceWarhead.cs
@@ -41,7 +41,5 @@ namespace OpenRA.Mods.RA
 			foreach (var cell in allCells)
 				resLayer.Destroy(cell);
 		}
-
-		public override float EffectivenessAgainst(ActorInfo ai) { return 1f; }
 	}
 }
diff --git a/OpenRA.Mods.RA/Warheads/LeaveSmudgeWarhead.cs b/OpenRA.Mods.RA/Warheads/LeaveSmudgeWarhead.cs
index eea2c92e59..2b051f5555 100644
--- a/OpenRA.Mods.RA/Warheads/LeaveSmudgeWarhead.cs
+++ b/OpenRA.Mods.RA/Warheads/LeaveSmudgeWarhead.cs
@@ -52,7 +52,5 @@ namespace OpenRA.Mods.RA
 				smudgeLayer.AddSmudge(sc);
 			}
 		}
-
-		public override float EffectivenessAgainst(ActorInfo ai) { return 1f; }
 	}
 }