diff --git a/Engine.Core/GameManager.cs b/Engine.Core/GameManager.cs
index 4aa725a..5aa3bd0 100644
--- a/Engine.Core/GameManager.cs
+++ b/Engine.Core/GameManager.cs
@@ -49,8 +49,8 @@ public class GameManager : BaseEntity, IGameManager
         if (!hierarchyObject.Initialize())
             throw new Exception($"{hierarchyObject.Name} can't be initialized");
 
-        foreach (IHierarchyObject child in hierarchyObject.Children)
-            Register(child);
+        for (int i = 0; i < hierarchyObject.Children.Count; i++)
+            Register(hierarchyObject.Children[i]);
 
         _hierarchyObjects.Add(hierarchyObject);
 
@@ -75,8 +75,8 @@ public class GameManager : BaseEntity, IGameManager
         hierarchyObject.OnFinalized -= OnHierarchyObjectFinalize;
         hierarchyObject.OnExitedHierarchy -= OnHierarchyObjectExitedHierarchy;
 
-        foreach (IHierarchyObject child in hierarchyObject.Children)
-            Remove(child);
+        for (int i = hierarchyObject.Children.Count - 1; i >= 0; i--)
+            Remove(hierarchyObject.Children[i]);
 
         _hierarchyObjects.Remove(hierarchyObject);
         hierarchyObject.SetParent(null);