diff --git a/OpenRA.Mods.Common/Activities/RepairBuilding.cs b/OpenRA.Mods.Common/Activities/RepairBuilding.cs
index 3a88543503..e364f832ad 100644
--- a/OpenRA.Mods.Common/Activities/RepairBuilding.cs
+++ b/OpenRA.Mods.Common/Activities/RepairBuilding.cs
@@ -21,6 +21,7 @@ namespace OpenRA.Mods.Common.Activities
 
 		Actor enterActor;
 		IHealth enterHealth;
+		EngineerRepairable enterEngineerRepariable;
 
 		public RepairBuilding(Actor self, Target target, EngineerRepairInfo info)
 			: base(self, target, Color.Yellow)
@@ -32,11 +33,12 @@ namespace OpenRA.Mods.Common.Activities
 		{
 			enterActor = targetActor;
 			enterHealth = targetActor.TraitOrDefault<IHealth>();
+			enterEngineerRepariable = targetActor.TraitOrDefault<EngineerRepairable>();
 
 			// Make sure we can still repair the target before entering
 			// (but not before, because this may stop the actor in the middle of nowhere)
 			var stance = self.Owner.Stances[enterActor.Owner];
-			if (enterHealth == null || enterHealth.DamageState == DamageState.Undamaged || !info.ValidStances.HasStance(stance))
+			if (enterHealth == null || enterHealth.DamageState == DamageState.Undamaged || enterEngineerRepariable == null || enterEngineerRepariable.IsTraitDisabled || !info.ValidStances.HasStance(stance))
 			{
 				Cancel(self, true);
 				return false;
@@ -52,6 +54,9 @@ namespace OpenRA.Mods.Common.Activities
 			if (targetActor != enterActor)
 				return;
 
+			if (enterEngineerRepariable.IsTraitDisabled)
+				return;
+
 			if (enterHealth.DamageState == DamageState.Undamaged)
 				return;
 
diff --git a/OpenRA.Mods.Common/Traits/EngineerRepair.cs b/OpenRA.Mods.Common/Traits/EngineerRepair.cs
index 6e1df7c529..3cf150b3d8 100644
--- a/OpenRA.Mods.Common/Traits/EngineerRepair.cs
+++ b/OpenRA.Mods.Common/Traits/EngineerRepair.cs
@@ -108,11 +108,11 @@ namespace OpenRA.Mods.Common.Traits
 
 			public override bool CanTargetActor(Actor self, Actor target, TargetModifiers modifiers, ref string cursor)
 			{
-				var engineerRepairable = target.Info.TraitInfoOrDefault<EngineerRepairableInfo>();
-				if (engineerRepairable == null)
+				var engineerRepairable = target.TraitOrDefault<EngineerRepairable>();
+				if (engineerRepairable == null || engineerRepairable.IsTraitDisabled)
 					return false;
 
-				if (!engineerRepairable.Types.IsEmpty && !engineerRepairable.Types.Overlaps(info.Types))
+				if (!engineerRepairable.Info.Types.IsEmpty && !engineerRepairable.Info.Types.Overlaps(info.Types))
 					return false;
 
 				if (!info.ValidStances.HasStance(self.Owner.Stances[target.Owner]))
@@ -126,6 +126,10 @@ namespace OpenRA.Mods.Common.Traits
 
 			public override bool CanTargetFrozenActor(Actor self, FrozenActor target, TargetModifiers modifiers, ref string cursor)
 			{
+				// TODO: FrozenActors don't yet have a way of caching conditions, so we can't filter disabled traits
+				// This therefore assumes that all EngineerRepairable traits are enabled, which is probably wrong.
+				// Actors with FrozenUnderFog should therefore not disable the EngineerRepairable trait if
+				// ValidStances includes Enemy actors.
 				var engineerRepairable = target.Info.TraitInfoOrDefault<EngineerRepairableInfo>();
 				if (engineerRepairable == null)
 					return false;
diff --git a/OpenRA.Mods.Common/Traits/EngineerRepairable.cs b/OpenRA.Mods.Common/Traits/EngineerRepairable.cs
index 6105ceafc7..3d9fcca231 100644
--- a/OpenRA.Mods.Common/Traits/EngineerRepairable.cs
+++ b/OpenRA.Mods.Common/Traits/EngineerRepairable.cs
@@ -17,11 +17,17 @@ namespace OpenRA.Mods.Common.Traits
 	public class EngineerRepairType { }
 
 	[Desc("Eligible for instant repair.")]
-	class EngineerRepairableInfo : TraitInfo<EngineerRepairable>
+	class EngineerRepairableInfo : ConditionalTraitInfo
 	{
 		[Desc("Actors with these Types under EngineerRepair trait can repair me.")]
 		public readonly BitSet<EngineerRepairType> Types = default(BitSet<EngineerRepairType>);
+
+		public override object Create(ActorInitializer init) { return new EngineerRepairable(init, this); }
 	}
 
-	class EngineerRepairable { }
+	class EngineerRepairable : ConditionalTrait<EngineerRepairableInfo>
+	{
+		public EngineerRepairable(ActorInitializer init, EngineerRepairableInfo info)
+			: base(info) { }
+	}
 }