diff --git a/game/factions/faction.py b/game/factions/faction.py
index a7b7de12..70721f8d 100644
--- a/game/factions/faction.py
+++ b/game/factions/faction.py
@@ -243,17 +243,18 @@ class Faction:
             faction.doctrine = MODERN_DOCTRINE
 
         # Load the building set
+        faction.building_set = []
         building_set = json.get("building_set", "default")
         if building_set == "default":
-            faction.building_set = DEFAULT_AVAILABLE_BUILDINGS
+            faction.building_set.extend(DEFAULT_AVAILABLE_BUILDINGS)
         elif building_set == "ww2free":
-            faction.building_set = WW2_FREE
+            faction.building_set.extend(WW2_FREE)
         elif building_set == "ww2ally":
-            faction.building_set = WW2_ALLIES_BUILDINGS
+            faction.building_set.extend(WW2_ALLIES_BUILDINGS)
         elif building_set == "ww2germany":
-            faction.building_set = WW2_GERMANY_BUILDINGS
+            faction.building_set.extend(WW2_GERMANY_BUILDINGS)
         else:
-            faction.building_set = DEFAULT_AVAILABLE_BUILDINGS
+            faction.building_set.extend(DEFAULT_AVAILABLE_BUILDINGS)
 
         # Add required buildings for the game logic (e.g. ammo, factory..)
         faction.building_set.extend(REQUIRED_BUILDINGS)