diff --git a/WoWsShipBuilder.Common/DataContainers/Ship/ManeuverabilityDataContainer.cs b/WoWsShipBuilder.Common/DataContainers/Ship/ManeuverabilityDataContainer.cs
index 9e1ad3d8d..de97c1355 100644
--- a/WoWsShipBuilder.Common/DataContainers/Ship/ManeuverabilityDataContainer.cs
+++ b/WoWsShipBuilder.Common/DataContainers/Ship/ManeuverabilityDataContainer.cs
@@ -67,10 +67,10 @@ public static ManeuverabilityDataContainer FromShip(Ship ship, List<ShipUpgrade>
         decimal maxSpeedModifier = modifiers.FindModifiers("speedCoef", true).Aggregate(1m, (current, modifier) => current * (decimal)modifier);
         maxSpeedModifier = modifiers.FindModifiers("shipSpeedCoeff", true).Aggregate(maxSpeedModifier, (current, modifier) => current * (decimal)modifier);
 
-        var speedBoostModifier = modifiers.FindModifiers("speedBoost_boostCoeff", true).Sum(); // Speed boost is additive
+        var speedBoostModifier = modifiers.FindModifiers("speedBoost_boostCoeff", true).Sum();
         if (speedBoostModifier != 0)
         {
-            maxSpeedModifier *= (decimal)(1 + speedBoostModifier + modifiers.FindModifiers("boostCoeffForsage").Sum()); // needed for Halland UU
+            maxSpeedModifier += (decimal)(1 + speedBoostModifier + modifiers.FindModifiers("boostCoeffForsage").Sum()); // Speed boost is additive, Halland UU bonus only applies if regular speed boost is active
         }
 
         decimal maxDiveSpeedModifier = modifiers.FindModifiers("maxBuoyancySpeedCoeff", true).Aggregate(1m, (current, modifier) => current * (decimal)modifier);