diff --git a/Engine.Core/Extensions/BehaviourExtensions.cs b/Engine.Core/Extensions/BehaviourExtensions.cs
index 1c89699..f1734e7 100644
--- a/Engine.Core/Extensions/BehaviourExtensions.cs
+++ b/Engine.Core/Extensions/BehaviourExtensions.cs
@@ -20,7 +20,7 @@ public static class BehaviourExtensions
         return behaviour is not null;
     }
 
-    public static void FindBehaviours<T>(this IEnumerable<IUniverseObject> universeObjects, List<T> behaviours) where T : class
+    public static void FindBehaviours<T>(this IEnumerable<IUniverseObject> universeObjects, IList<T> behaviours) where T : class
     {
         behaviours.Clear();
         List<T> cache = [];
diff --git a/Engine.Core/Extensions/UniverseObjectExtensions.cs b/Engine.Core/Extensions/UniverseObjectExtensions.cs
index bacd7e9..437a72c 100644
--- a/Engine.Core/Extensions/UniverseObjectExtensions.cs
+++ b/Engine.Core/Extensions/UniverseObjectExtensions.cs
@@ -29,7 +29,7 @@ public static class UniverseObjectExtensions
         return behaviour is not null;
     }
 
-    public static void GetUniverseObjects<T>(this IEnumerable<IUniverseObject> universeObjects, List<T> behaviours) where T : class
+    public static void GetUniverseObjects<T>(this IEnumerable<IUniverseObject> universeObjects, IList<T> behaviours) where T : class
     {
         behaviours.Clear();
         foreach (IUniverseObject universeObject in universeObjects)