diff --git a/Source/ModuleROHeatshield.cs b/Source/ModuleROHeatshield.cs
index dd2482a..bb4648e 100644
--- a/Source/ModuleROHeatshield.cs
+++ b/Source/ModuleROHeatshield.cs
@@ -353,8 +353,7 @@ public bool IsConfigUnlocked(string configName)
 
         public bool PurchaseConfig(PartUpgradeHandler.Upgrade upgd)
         {
-            CurrencyModifierQuery cmq = CurrencyModifierQuery.RunQuery(TransactionReasons.RnDPartPurchase, -upgd.entryCost, 0, 0);
-            if (!cmq.CanAfford())
+            if (!CanAffordEntryCost(upgd.entryCost))
                 return false;
 
             PartUpgradeManager.Handler.SetUnlocked(upgd.name, true);
@@ -464,7 +463,7 @@ private PartResource EnsureAblatorResource(string name)
         }
 
         /// <summary>
-        /// Called from RP0KCT
+        /// Called from RP-1
         /// </summary>
         /// <param name="validationError"></param>
         /// <param name="canBeResolved"></param>
@@ -497,7 +496,7 @@ public virtual bool Validate(out string validationError, out bool canBeResolved,
         }
 
         /// <summary>
-        /// Called from RP0KCT
+        /// Called from RP-1
         /// </summary>
         /// <returns></returns>
         public virtual bool ResolveValidationError()
@@ -508,6 +507,17 @@ public virtual bool ResolveValidationError()
             return PurchaseConfig(upgd);
         }
 
+        /// <summary>
+        /// NOTE: Harmony-patched from RP-1 to factor in unlock credit.
+        /// </summary>
+        /// <param name="cost"></param>
+        /// <returns></returns>
+        private static bool CanAffordEntryCost(float cost)
+        {
+            CurrencyModifierQuery cmq = CurrencyModifierQuery.RunQuery(TransactionReasons.RnDPartPurchase, -cost, 0, 0);
+            return cmq.CanAfford();
+        }
+
         #endregion Custom Methods
     }
 }