diff --git a/src/main/java/io/spring/api/ArticleApi.java b/src/main/java/io/spring/api/ArticleApi.java
index c80afa31d..92b70fcac 100644
--- a/src/main/java/io/spring/api/ArticleApi.java
+++ b/src/main/java/io/spring/api/ArticleApi.java
@@ -33,7 +33,7 @@ public class ArticleApi {
   private ArticleCommandService articleCommandService;
 
   @GetMapping
-  public ResponseEntity<?> article(
+  public ResponseEntity<Map<String, Object>> article(
       @PathVariable("slug") String slug, @AuthenticationPrincipal User user) {
     return articleQueryService
         .findBySlug(slug, user)
@@ -42,7 +42,7 @@ public ResponseEntity<?> article(
   }
 
   @PutMapping
-  public ResponseEntity<?> updateArticle(
+  public ResponseEntity<Map<String, Object>> updateArticle(
       @PathVariable("slug") String slug,
       @AuthenticationPrincipal User user,
       @Valid @RequestBody UpdateArticleParam updateArticleParam) {
diff --git a/src/main/java/io/spring/api/CommentsApi.java b/src/main/java/io/spring/api/CommentsApi.java
index c5f7e77e9..6dd329f8e 100644
--- a/src/main/java/io/spring/api/CommentsApi.java
+++ b/src/main/java/io/spring/api/CommentsApi.java
@@ -38,7 +38,7 @@ public class CommentsApi {
   private CommentQueryService commentQueryService;
 
   @PostMapping
-  public ResponseEntity<?> createComment(
+  public ResponseEntity<Map<String, Object>> createComment(
       @PathVariable("slug") String slug,
       @AuthenticationPrincipal User user,
       @Valid @RequestBody NewCommentParam newCommentParam) {
diff --git a/src/main/java/io/spring/api/exception/InvalidRequestException.java b/src/main/java/io/spring/api/exception/InvalidRequestException.java
index 68b6c868a..7360d717e 100644
--- a/src/main/java/io/spring/api/exception/InvalidRequestException.java
+++ b/src/main/java/io/spring/api/exception/InvalidRequestException.java
@@ -4,7 +4,7 @@
 
 @SuppressWarnings("serial")
 public class InvalidRequestException extends RuntimeException {
-  private final Errors errors;
+  private final transient Errors errors;
 
   public InvalidRequestException(Errors errors) {
     super("");
diff --git a/src/main/java/io/spring/core/article/Article.java b/src/main/java/io/spring/core/article/Article.java
index f23c2c6d5..988b24bbb 100644
--- a/src/main/java/io/spring/core/article/Article.java
+++ b/src/main/java/io/spring/core/article/Article.java
@@ -65,6 +65,6 @@ public void update(String title, String description, String body) {
   }
 
   public static String toSlug(String title) {
-    return title.toLowerCase().replaceAll("[\\&|[\\uFE30-\\uFFA0]|\\’|\\”|\\s\\?\\,\\.]+", "-");
+    return title.toLowerCase().replaceAll("[&|\\uFE30-\\uFFA0’”\\s?,.]+", "-");
   }
 }
diff --git a/src/test/java/io/spring/infrastructure/service/DefaultJwtServiceTest.java b/src/test/java/io/spring/infrastructure/service/DefaultJwtServiceTest.java
index 12929118a..b2261705e 100644
--- a/src/test/java/io/spring/infrastructure/service/DefaultJwtServiceTest.java
+++ b/src/test/java/io/spring/infrastructure/service/DefaultJwtServiceTest.java
@@ -13,7 +13,8 @@ public class DefaultJwtServiceTest {
 
   @BeforeEach
   public void setUp() {
-    jwtService = new DefaultJwtService("123123123123123123123123123123123123123123123123123123123123", 3600);
+    jwtService =
+        new DefaultJwtService("123123123123123123123123123123123123123123123123123123123123", 3600);
   }
 
   @Test