diff --git a/core/src/com/unciv/models/ruleset/Building.kt b/core/src/com/unciv/models/ruleset/Building.kt
index cfc6c8fdee..71e797ab42 100644
--- a/core/src/com/unciv/models/ruleset/Building.kt
+++ b/core/src/com/unciv/models/ruleset/Building.kt
@@ -42,7 +42,7 @@ class Building : NamedStats(), IConstruction {
     private var hurryCostModifier = 0
     var isWonder = false
     var isNationalWonder = false
-    private var requiredBuilding: String? = null
+    var requiredBuilding: String? = null
     var requiredBuildingInAllCities: String? = null
 
     /** A strategic resource that will be consumed by this building */
diff --git a/core/src/com/unciv/models/ruleset/Ruleset.kt b/core/src/com/unciv/models/ruleset/Ruleset.kt
index 3d0882276f..3cc849e0d2 100644
--- a/core/src/com/unciv/models/ruleset/Ruleset.kt
+++ b/core/src/com/unciv/models/ruleset/Ruleset.kt
@@ -266,6 +266,8 @@ class Ruleset {
                 lines += "${building.name} requires resource ${building.requiredResource} which does not exist!"
             if (building.replaces != null && !buildings.containsKey(building.replaces!!))
                 lines += "${building.name} replaces ${building.replaces} which does not exist!"
+            if (building.requiredBuilding != null && !buildings.containsKey(building.requiredBuilding!!))
+                lines += "${building.name} requires ${building.requiredBuilding} which does not exist!"
         }
 
         for (resource in tileResources.values) {