diff --git a/src/main/java/xyz/zhouxy/plusone/commons/model/dto/UnifiedResponse.java b/src/main/java/xyz/zhouxy/plusone/commons/model/dto/UnifiedResponse.java
index f5531eb..b8ab047 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/model/dto/UnifiedResponse.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/model/dto/UnifiedResponse.java
@@ -26,10 +26,10 @@ import javax.annotation.Nullable;
  */
 public class UnifiedResponse<T> {
 
-    private String code;
-    private String message;
+    private final String code;
+    private final String message;
 
-    private @Nullable T data;
+    private final @Nullable T data;
 
     // ================================
     // #region - Constructors