diff --git a/OpenRA.Mods.Cnc/Traits/AttackPopupTurreted.cs b/OpenRA.Mods.Cnc/Traits/AttackPopupTurreted.cs
index 1feba5c954..e8619bf553 100644
--- a/OpenRA.Mods.Cnc/Traits/AttackPopupTurreted.cs
+++ b/OpenRA.Mods.Cnc/Traits/AttackPopupTurreted.cs
@@ -112,7 +112,7 @@ namespace OpenRA.Mods.Cnc.Traits
 			}
 		}
 
-		public int GetDamageModifier(Actor attacker, Damage damage)
+		int IDamageModifier.GetDamageModifier(Actor attacker, Damage damage)
 		{
 			return state == PopupState.Closed ? info.ClosedDamageMultiplier : 100;
 		}
diff --git a/OpenRA.Mods.Common/Traits/Infantry/TerrainModifiesDamage.cs b/OpenRA.Mods.Common/Traits/Infantry/TerrainModifiesDamage.cs
index c06d4a2262..185cfb7880 100644
--- a/OpenRA.Mods.Common/Traits/Infantry/TerrainModifiesDamage.cs
+++ b/OpenRA.Mods.Common/Traits/Infantry/TerrainModifiesDamage.cs
@@ -41,7 +41,7 @@ namespace OpenRA.Mods.Common.Traits
 			this.self = self;
 		}
 
-		public int GetDamageModifier(Actor attacker, Damage damage)
+		int IDamageModifier.GetDamageModifier(Actor attacker, Damage damage)
 		{
 			if (attacker.Owner.IsAlliedWith(self.Owner) && damage.Value < 0 && !Info.ModifyHealing)
 				return FullDamage;
diff --git a/OpenRA.Mods.Common/Traits/Multipliers/DamageMultiplier.cs b/OpenRA.Mods.Common/Traits/Multipliers/DamageMultiplier.cs
index 87b107fe06..6ba58d0921 100644
--- a/OpenRA.Mods.Common/Traits/Multipliers/DamageMultiplier.cs
+++ b/OpenRA.Mods.Common/Traits/Multipliers/DamageMultiplier.cs
@@ -26,6 +26,6 @@ namespace OpenRA.Mods.Common.Traits
 		public DamageMultiplier(DamageMultiplierInfo info, string actorType)
 			: base(info, "DamageMultiplier", actorType) { }
 
-		public int GetDamageModifier(Actor attacker, Damage damage) { return GetModifier(); }
+		int IDamageModifier.GetDamageModifier(Actor attacker, Damage damage) { return GetModifier(); }
 	}
 }
diff --git a/OpenRA.Mods.Common/TraitsInterfaces.cs b/OpenRA.Mods.Common/TraitsInterfaces.cs
index 4bcf3f9bbb..357a73e954 100644
--- a/OpenRA.Mods.Common/TraitsInterfaces.cs
+++ b/OpenRA.Mods.Common/TraitsInterfaces.cs
@@ -203,6 +203,7 @@ namespace OpenRA.Mods.Common.Traits
 		string SequencePrefix { get; }
 	}
 
+	[RequireExplicitImplementation]
 	public interface IDamageModifier { int GetDamageModifier(Actor attacker, Damage damage); }
 	public interface ISpeedModifier { int GetSpeedModifier(); }
 	public interface IFirepowerModifier { int GetFirepowerModifier(); }