diff --git a/src/main/resources/mapper/PostRatingMapper.xml b/src/main/resources/mapper/PostRatingMapper.xml
index 097eeb8..bb13dd4 100644
--- a/src/main/resources/mapper/PostRatingMapper.xml
+++ b/src/main/resources/mapper/PostRatingMapper.xml
@@ -1,5 +1,10 @@
-<insert id="insertOrUpdate">
-    INSERT INTO post_ratings (user_id, post_id, rating)
-    VALUES (#{userId}, #{postId}, #{rating})
-    ON DUPLICATE KEY UPDATE rating = VALUES(rating)
-</insert>
\ No newline at end of file
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
+        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="com.example.mapper.PostRatingMapper">
+    <insert id="insertOrUpdate">
+        INSERT INTO post_ratings (user_id, post_id, rating)
+        VALUES (#{userId}, #{postId}, #{rating})
+        ON DUPLICATE KEY UPDATE rating = VALUES(rating)
+    </insert>
+</mapper>
\ No newline at end of file