diff --git a/Assets/Unity-Tools/ExcelResolver/Editor/Core/Data/ClassCodeData.cs b/Assets/Unity-Tools/ExcelResolver/Editor/Core/Data/ClassCodeData.cs
index 291f323..84e5345 100644
--- a/Assets/Unity-Tools/ExcelResolver/Editor/Core/Data/ClassCodeData.cs
+++ b/Assets/Unity-Tools/ExcelResolver/Editor/Core/Data/ClassCodeData.cs
@@ -24,11 +24,14 @@ namespace Tools.ExcelResolver.Editor
             fields.Clear();
             fields = null;
 
-            foreach (var fieldData in keyField)
+            if (keyField != null)
             {
-                fieldData?.Dispose();
+                foreach (var fieldData in keyField)
+                {
+                    fieldData?.Dispose();
+                }
+                keyField = null;
             }
-            keyField = null;
         }
     }
 }
\ No newline at end of file