diff --git a/Scripts/Editor/NodeEditorWindow.cs b/Scripts/Editor/NodeEditorWindow.cs
index db16033..a5cbf3f 100644
--- a/Scripts/Editor/NodeEditorWindow.cs
+++ b/Scripts/Editor/NodeEditorWindow.cs
@@ -22,7 +22,7 @@ namespace XNodeEditor {
         void OnFocus() {
             current = this;
             graphEditor = NodeGraphEditor.GetEditor(graph);
-            if (NodeEditorPreferences.GetSettings().autoSave) AssetDatabase.SaveAssets();
+            if (graphEditor != null && NodeEditorPreferences.GetSettings().autoSave) AssetDatabase.SaveAssets();
         }
 
         partial void OnEnable();