diff --git a/core/src/com/unciv/logic/city/CityStats.kt b/core/src/com/unciv/logic/city/CityStats.kt
index 6fd96f9d5e..7af4bc0c8c 100644
--- a/core/src/com/unciv/logic/city/CityStats.kt
+++ b/core/src/com/unciv/logic/city/CityStats.kt
@@ -265,10 +265,10 @@ class CityStats {
     private fun getStatsFromUniques(uniques: Sequence<Unique>): Stats {
         val stats = Stats()
 
-        for (unique in uniques) {
-            if ((unique.placeholderText == "[] in capital" && cityInfo.isCapital())
+        for (unique in uniques.toList()) { // Should help  mitigate getConstructionButtonDTOs concurrency problems.
+            if (unique.placeholderText == "[] in capital" && cityInfo.isCapital()
                     || unique.placeholderText == "[] in all cities"
-                    || (unique.placeholderText == "[] in all cities with a garrison" && cityInfo.getCenterTile().militaryUnit != null))
+                    || unique.placeholderText == "[] in all cities with a garrison" && cityInfo.getCenterTile().militaryUnit != null)
                 stats.add(unique.stats)
             if (unique.placeholderText == "[] per [] population in all cities") {
                 val amountOfEffects = (cityInfo.population.population / unique.params[1].toInt()).toFloat()
@@ -317,8 +317,11 @@ class CityStats {
         return stats
     }
 
-    private fun getStatPercentBonusesFromUniques(currentConstruction: IConstruction, uniques: Sequence<Unique>): Stats {
+    private fun getStatPercentBonusesFromUniques(currentConstruction: IConstruction, uniqueSequence: Sequence<Unique>): Stats {
         val stats = Stats()
+        val uniques = uniqueSequence.toList().asSequence()
+          // Since this is sometimes run from a different thread (getConstructionButtonDTOs),
+          // this helps mitigate concurrency problems.
 
         if (currentConstruction.name == Constants.settler && cityInfo.isCapital()
                 && uniques.any { it.text == "Training of settlers increased +50% in capital" })
diff --git a/core/src/com/unciv/logic/civilization/CivInfoStats.kt b/core/src/com/unciv/logic/civilization/CivInfoStats.kt
index a2a8d0a743..6291ba38d0 100644
--- a/core/src/com/unciv/logic/civilization/CivInfoStats.kt
+++ b/core/src/com/unciv/logic/civilization/CivInfoStats.kt
@@ -143,11 +143,14 @@ class CivInfoStats(val civInfo: CivilizationInfo){
         statMap["Luxury resources"]= civInfo.getCivResources().map { it.resource }
                 .count { it.resourceType === ResourceType.Luxury } * happinessPerUniqueLuxury
 
-        for(city in civInfo.cities){
-            for(keyvalue in city.cityStats.happinessList){
-                if(statMap.containsKey(keyvalue.key))
-                    statMap[keyvalue.key] = statMap[keyvalue.key]!!+keyvalue.value
-                else statMap[keyvalue.key] = keyvalue.value
+        for(city in civInfo.cities) {
+            // There appears to be a concurrency problem? In concurrent thread in ConstructionsTable.getConstructionButtonDTOs
+                // Literally no idea how, since happinessList is ONLY replaced, NEVER altered.
+                // Oh well, toList() should solve the problem, wherever it may come from.
+            for ((key, value) in city.cityStats.happinessList.toList()) {
+                if (statMap.containsKey(key))
+                    statMap[key] = statMap[key]!! + value
+                else statMap[key] = value
             }
         }