diff --git a/src/Luban.CSharp/TypeVisitors/IsRawNullableTypeVisitor.cs b/src/Luban.CSharp/TypeVisitors/IsRawNullableTypeVisitor.cs
index 6316baed..b909247d 100644
--- a/src/Luban.CSharp/TypeVisitors/IsRawNullableTypeVisitor.cs
+++ b/src/Luban.CSharp/TypeVisitors/IsRawNullableTypeVisitor.cs
@@ -34,6 +34,6 @@ public override bool Accept(TMap type)
 
     public override bool Accept(TBean type)
     {
-        return true;
+        return !type.DefBean.IsValueType;
     }
 }