diff --git a/Engine.Core/Systems/UniverseEntranceManager.cs b/Engine.Core/Systems/UniverseEntranceManager.cs
index 460647b..60aea30 100644
--- a/Engine.Core/Systems/UniverseEntranceManager.cs
+++ b/Engine.Core/Systems/UniverseEntranceManager.cs
@@ -19,6 +19,7 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
         // FIXME: This causes an issue when the UniverseEntranceManager is already attached to a UniverseObject then registered into a Universe,
         // the enter/exit universe collectors call OnUniverseObjectRegistered internally on Assign, but since the Universe calls the OnUniverseObjectRegistered
         // event it tries to call OnUniverseObjectRegistered again on the same object, causing a duplicate entry error.
+        Debug.Assert.AssertTrue(BehaviourController.Count == 1, $"{nameof(UniverseEntranceManager)} must be in it's own {nameof(IUniverseObject)} with no other {nameof(IBehaviour)}s attached at the moment. Failing to do so might cause instantiation or serialization issues.");
         enterUniverses.Assign(universe);
         exitUniverses.Assign(universe);