diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawer.cs
index c7e70c6..2309b1d 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawer.cs
@@ -8,14 +8,22 @@ namespace Alchemy.Editor
     /// </summary>
     public abstract class HierarchyDrawer
     {
+#if UNITY_6000_4_OR_NEWER
+        public abstract void OnGUI(EntityId instanceID, Rect selectionRect);
+#else
         public abstract void OnGUI(int instanceID, Rect selectionRect);
+#endif
 
         protected static Rect GetBackgroundRect(Rect selectionRect)
         {
             return selectionRect.AddXMax(20f);
         }
 
+#if UNITY_6000_4_OR_NEWER
+        protected static void DrawBackground(EntityId instanceID, Rect selectionRect)
+#else
         protected static void DrawBackground(int instanceID, Rect selectionRect)
+#endif
         {
             var backgroundRect = GetBackgroundRect(selectionRect);
 
@@ -39,4 +47,4 @@ protected static void DrawBackground(int instanceID, Rect selectionRect)
             EditorGUI.DrawRect(backgroundRect, backgroundColor);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawerInitializer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawerInitializer.cs
index c535372..99a80b1 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawerInitializer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyDrawerInitializer.cs
@@ -15,8 +15,12 @@ static void Init()
 
             foreach (var drawer in drawers)
             {
+#if UNITY_6000_4_OR_NEWER
+                EditorApplication.hierarchyWindowItemByEntityIdOnGUI += drawer.OnGUI;
+#else
                 EditorApplication.hierarchyWindowItemOnGUI += drawer.OnGUI;
+#endif
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyHeaderDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyHeaderDrawer.cs
index ca5ba37..18c26ca 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyHeaderDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyHeaderDrawer.cs
@@ -9,7 +9,11 @@ public sealed class HierarchyHeaderDrawer : HierarchyDrawer
         static Color HeaderColor => EditorGUIUtility.isProSkin ? new(0.45f, 0.45f, 0.45f, 0.5f) : new(0.55f, 0.55f, 0.55f, 0.5f);
         static GUIStyle labelStyle;
 
+#if UNITY_6000_4_OR_NEWER
+        public override void OnGUI(EntityId instanceID, Rect selectionRect)
+#else
         public override void OnGUI(int instanceID, Rect selectionRect)
+#endif
         {
             if (labelStyle == null)
             {
@@ -20,7 +24,11 @@ public override void OnGUI(int instanceID, Rect selectionRect)
                 };
             }
 
+#if UNITY_6000_4_OR_NEWER
+            var gameObject = EditorUtility.EntityIdToObject(instanceID) as GameObject;
+#else
             var gameObject = EditorUtility.InstanceIDToObject(instanceID) as GameObject;
+#endif
             if (gameObject == null) return;
             if (!gameObject.TryGetComponent<HierarchyHeader>(out _)) return;
 
@@ -31,4 +39,4 @@ public override void OnGUI(int instanceID, Rect selectionRect)
             EditorGUI.LabelField(headerRect, gameObject.name, labelStyle);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyRowSeparatorDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyRowSeparatorDrawer.cs
index 3ff57b9..b6719b5 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyRowSeparatorDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyRowSeparatorDrawer.cs
@@ -5,7 +5,11 @@ namespace Alchemy.Editor
 {
     public class HierarchyRowSeparatorDrawer : HierarchyDrawer
     {
+#if UNITY_6000_4_OR_NEWER
+        public override void OnGUI(EntityId instanceID, Rect selectionRect)
+#else
         public override void OnGUI(int instanceID, Rect selectionRect)
+#endif
         {
             var settings = AlchemySettings.GetOrCreateSettings();
             if (!settings.ShowSeparator) return;
@@ -21,4 +25,4 @@ public override void OnGUI(int instanceID, Rect selectionRect)
             EditorGUI.DrawRect(selectionRect, Mathf.FloorToInt((selectionRect.y - 4) / 16 % 2) == 0 ? settings.EvenRowColor : settings.OddRowColor);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchySeparatorDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchySeparatorDrawer.cs
index 0da41af..00bf1f7 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchySeparatorDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchySeparatorDrawer.cs
@@ -8,9 +8,17 @@ public sealed class HierarchySeparatorDrawer : HierarchyDrawer
     {
         static Color SeparatorColor => new(0.5f, 0.5f, 0.5f);
 
+#if UNITY_6000_4_OR_NEWER
+        public override void OnGUI(EntityId instanceID, Rect selectionRect)
+#else
         public override void OnGUI(int instanceID, Rect selectionRect)
+#endif
         {
+#if UNITY_6000_4_OR_NEWER
+            var gameObject = EditorUtility.EntityIdToObject(instanceID) as GameObject;
+#else
             var gameObject = EditorUtility.InstanceIDToObject(instanceID) as GameObject;
+#endif
             if (gameObject == null) return;
             if (!gameObject.TryGetComponent<HierarchySeparator>(out _)) return;
 
@@ -20,4 +28,4 @@ public override void OnGUI(int instanceID, Rect selectionRect)
             EditorGUI.DrawRect(lineRect, SeparatorColor);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyToggleDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyToggleDrawer.cs
index 46af3d2..47ca2c7 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyToggleDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyToggleDrawer.cs
@@ -7,9 +7,17 @@ namespace Alchemy.Editor
 {
     public sealed class HierarchyToggleDrawer : HierarchyDrawer
     {
+#if UNITY_6000_4_OR_NEWER
+        public override void OnGUI(EntityId instanceID, Rect selectionRect)
+#else
         public override void OnGUI(int instanceID, Rect selectionRect)
+#endif
         {
+#if UNITY_6000_4_OR_NEWER
+            var gameObject = EditorUtility.EntityIdToObject(instanceID) as GameObject;
+#else
             var gameObject = EditorUtility.InstanceIDToObject(instanceID) as GameObject;
+#endif
             if (gameObject == null) return;
             if (gameObject.TryGetComponent<HierarchyObject>(out _)) return;
 
@@ -100,4 +108,4 @@ private static bool IsNewPrefabWorkflow()
         }
     }
 
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyTreeMapDrawer.cs b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyTreeMapDrawer.cs
index 6de84b6..c285287 100644
--- a/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyTreeMapDrawer.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Hierarchy/HierarchyTreeMapDrawer.cs
@@ -61,9 +61,17 @@ public static Texture2D TreeMapLine
             }
         }
 
+#if UNITY_6000_4_OR_NEWER
+        public override void OnGUI(EntityId instanceID, Rect selectionRect)
+#else
         public override void OnGUI(int instanceID, Rect selectionRect)
+#endif
         {
+#if UNITY_6000_4_OR_NEWER
+            var gameObject = EditorUtility.EntityIdToObject(instanceID) as GameObject;
+#else
             var gameObject = EditorUtility.InstanceIDToObject(instanceID) as GameObject;
+#endif
             if (gameObject == null) return;
 
             var settings = AlchemySettings.GetOrCreateSettings();
@@ -137,4 +145,4 @@ public override void OnGUI(int instanceID, Rect selectionRect)
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Alchemy/Assets/Alchemy/Editor/Internal/SerializeReferenceDropdown.cs b/Alchemy/Assets/Alchemy/Editor/Internal/SerializeReferenceDropdown.cs
index 75dcaf4..d091306 100644
--- a/Alchemy/Assets/Alchemy/Editor/Internal/SerializeReferenceDropdown.cs
+++ b/Alchemy/Assets/Alchemy/Editor/Internal/SerializeReferenceDropdown.cs
@@ -102,7 +102,11 @@ public static void AddTo(AdvancedDropdownItem root, IEnumerable<Type> types)
 
         static AdvancedDropdownItem GetItem(AdvancedDropdownItem parent, string name)
         {
+#if UNITY_6000_5_OR_NEWER
+            foreach (AdvancedDropdownItem item in parent.childList)
+#else
             foreach (AdvancedDropdownItem item in parent.children)
+#endif
             {
                 if (item.name == name) return item;
             }
@@ -150,4 +154,4 @@ static string[] GetSplittedTypePath(Type type)
         }
 
     }
-}
\ No newline at end of file
+}