diff --git a/OpenRA.Mods.Common/AI/AttackOrFleeFuzzy.cs b/OpenRA.Mods.Common/AI/AttackOrFleeFuzzy.cs
index 7ce7dc1704..c6c8183bb8 100644
--- a/OpenRA.Mods.Common/AI/AttackOrFleeFuzzy.cs
+++ b/OpenRA.Mods.Common/AI/AttackOrFleeFuzzy.cs
@@ -198,7 +198,8 @@ namespace OpenRA.Mods.Common.AI
 			if (sumOfMaxHp == 0)
 				return 0.0f;
 
-			return (sumOfHp * normalizeByValue) / sumOfMaxHp;
+			// Cast to long to avoid overflow when multiplying by the health
+			return (int)((long)sumOfHp * normalizeByValue / sumOfMaxHp);
 		}
 
 		static float RelativePower(IEnumerable<Actor> own, IEnumerable<Actor> enemy)
diff --git a/OpenRA.Mods.Common/Activities/CaptureActor.cs b/OpenRA.Mods.Common/Activities/CaptureActor.cs
index aa37f629da..91d7295aae 100644
--- a/OpenRA.Mods.Common/Activities/CaptureActor.cs
+++ b/OpenRA.Mods.Common/Activities/CaptureActor.cs
@@ -58,7 +58,9 @@ namespace OpenRA.Mods.Common.Activities
 					return;
 
 				var capturesInfo = activeCaptures.Info;
-				var lowEnoughHealth = health.HP <= capturable.Info.CaptureThreshold * health.MaxHP / 100;
+
+				// Cast to long to avoid overflow when multiplying by the health
+				var lowEnoughHealth = health.HP <= (int)(capturable.Info.CaptureThreshold * (long)health.MaxHP / 100);
 				if (!capturesInfo.Sabotage || lowEnoughHealth || actor.Owner.NonCombatant)
 				{
 					var oldOwner = actor.Owner;
@@ -80,7 +82,8 @@ namespace OpenRA.Mods.Common.Activities
 				}
 				else
 				{
-					var damage = health.MaxHP * capturesInfo.SabotageHPRemoval / 100;
+					// Cast to long to avoid overflow when multiplying by the health
+					var damage = (int)((long)health.MaxHP * capturesInfo.SabotageHPRemoval / 100);
 					actor.InflictDamage(self, new Damage(damage));
 				}
 
diff --git a/OpenRA.Mods.Common/Activities/Repair.cs b/OpenRA.Mods.Common/Activities/Repair.cs
index 2dd1a6d5da..57e4e86018 100644
--- a/OpenRA.Mods.Common/Activities/Repair.cs
+++ b/OpenRA.Mods.Common/Activities/Repair.cs
@@ -98,7 +98,9 @@ namespace OpenRA.Mods.Common.Activities
 			{
 				var unitCost = self.Info.TraitInfo<ValuedInfo>().Cost;
 				var hpToRepair = repairsUnits.Info.HpPerStep;
-				var cost = Math.Max(1, (hpToRepair * unitCost * repairsUnits.Info.ValuePercentage) / (health.MaxHP * 100));
+
+				// Cast to long to avoid overflow when multiplying by the health
+				var cost = Math.Max(1, (int)(((long)hpToRepair * unitCost * repairsUnits.Info.ValuePercentage) / (health.MaxHP * 100L)));
 
 				if (!played)
 				{
diff --git a/OpenRA.Mods.Common/Traits/Buildings/RepairableBuilding.cs b/OpenRA.Mods.Common/Traits/Buildings/RepairableBuilding.cs
index d55484a088..5b51b16713 100644
--- a/OpenRA.Mods.Common/Traits/Buildings/RepairableBuilding.cs
+++ b/OpenRA.Mods.Common/Traits/Buildings/RepairableBuilding.cs
@@ -115,7 +115,9 @@ namespace OpenRA.Mods.Common.Traits
 
 				// The cost is the same regardless of the amount of people repairing
 				var hpToRepair = Math.Min(Info.RepairStep, health.MaxHP - health.HP);
-				var cost = Math.Max(1, (hpToRepair * Info.RepairPercent * buildingValue) / (health.MaxHP * 100));
+
+				// Cast to long to avoid overflow when multiplying by the health
+				var cost = Math.Max(1, (int)(((long)hpToRepair * Info.RepairPercent * buildingValue) / (health.MaxHP * 100L)));
 
 				// TakeCash will return false if the player can't pay, and will stop him from contributing this Tick
 				var activePlayers = Repairers.Count(player => player.PlayerActor.Trait<PlayerResources>().TakeCash(cost, true));
diff --git a/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs b/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
index 3e3992801c..5cfb048aa7 100644
--- a/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
+++ b/OpenRA.Mods.Common/Traits/DamagedByTerrain.cs
@@ -69,7 +69,8 @@ namespace OpenRA.Mods.Common.Traits
 			if (totalTiles == 0)
 				return;
 
-			damageThreshold = (Info.DamageThreshold * health.MaxHP + (100 - Info.DamageThreshold) * safeTiles * health.MaxHP / totalTiles) / 100;
+			// Cast to long to avoid overflow when multiplying by the health
+			damageThreshold = (int)((Info.DamageThreshold * (long)health.MaxHP + (100 - Info.DamageThreshold) * safeTiles * (long)health.MaxHP / totalTiles) / 100);
 
 			// Actors start with maximum damage applied
 			var delta = health.HP - damageThreshold;
diff --git a/OpenRA.Mods.Common/Traits/Health.cs b/OpenRA.Mods.Common/Traits/Health.cs
index 44097467f4..96491bc8b4 100644
--- a/OpenRA.Mods.Common/Traits/Health.cs
+++ b/OpenRA.Mods.Common/Traits/Health.cs
@@ -43,7 +43,8 @@ namespace OpenRA.Mods.Common.Traits
 			Info = info;
 			MaxHP = info.HP > 0 ? info.HP : 1;
 
-			hp = init.Contains<HealthInit>() ? init.Get<HealthInit, int>() * MaxHP / 100 : MaxHP;
+			// Cast to long to avoid overflow when multiplying by the health
+			hp = init.Contains<HealthInit>() ? (int)(init.Get<HealthInit, int>() * (long)MaxHP / 100) : MaxHP;
 
 			DisplayHP = hp;
 		}