diff --git a/OpenRA.Mods.RA/Activities/Repair.cs b/OpenRA.Mods.RA/Activities/Repair.cs
index ec77a0082b..0e07c53563 100644
--- a/OpenRA.Mods.RA/Activities/Repair.cs
+++ b/OpenRA.Mods.RA/Activities/Repair.cs
@@ -37,7 +37,7 @@ namespace OpenRA.Mods.RA.Activities
 				var repairsUnits = host.Info.Traits.Get<RepairsUnitsInfo>();
 				var unitCost = self.Info.Traits.Get<ValuedInfo>().Cost;
 				var hpToRepair = repairsUnits.HpPerStep;
-				var cost = (hpToRepair * unitCost * repairsUnits.ValuePercentage) / (health.MaxHP * 100);
+				var cost = Math.Max(1, (hpToRepair * unitCost * repairsUnits.ValuePercentage) / (health.MaxHP * 100));
 
 				if (!self.Owner.PlayerActor.Trait<PlayerResources>().TakeCash(cost))
 				{