diff --git a/src/app/features/article/models/comment.model.ts b/src/app/features/article/models/comment.model.ts
index 6a6350b5b..6621c22dd 100644
--- a/src/app/features/article/models/comment.model.ts
+++ b/src/app/features/article/models/comment.model.ts
@@ -4,5 +4,6 @@ export interface Comment {
   id: string;
   body: string;
   createdAt: string;
+  updatedAt: string;
   author: Profile;
 }
diff --git a/src/app/features/article/services/articles.service.spec.ts b/src/app/features/article/services/articles.service.spec.ts
index a6a8af9a6..d17580730 100644
--- a/src/app/features/article/services/articles.service.spec.ts
+++ b/src/app/features/article/services/articles.service.spec.ts
@@ -147,6 +147,30 @@ describe('ArticlesService', () => {
       const req = httpMock.expectOne('/articles');
       req.flush({ articles: [], articlesCount: 0 });
     });
+
+    it('should skip undefined filter values', () => {
+      const config: ArticleListConfig = {
+        type: 'all',
+        filters: {
+          tag: 'angular',
+          author: undefined,
+          limit: 10,
+        },
+      };
+
+      service.query(config).subscribe();
+
+      const req = httpMock.expectOne(request => {
+        return (
+          request.url === '/articles' &&
+          request.params.get('tag') === 'angular' &&
+          request.params.get('author') === null &&
+          request.params.get('limit') === '10'
+        );
+      });
+
+      req.flush({ articles: mockArticleList, articlesCount: 2 });
+    });
   });
 
   describe('get', () => {
@@ -255,12 +279,18 @@ describe('ArticlesService', () => {
   describe('unfavorite', () => {
     it('should unfavorite an article', async () => {
       const slug = 'article-to-unfavorite';
+      const unfavoritedArticle = {
+        ...mockArticle,
+        favorited: false,
+        favoritesCount: 4,
+      };
       const promise = firstValueFrom(service.unfavorite(slug));
       const req = httpMock.expectOne(`/articles/${slug}/favorite`);
       expect(req.request.method).toBe('DELETE');
-      req.flush(null);
-      await promise;
-      expect(true).toBe(true);
+      req.flush({ article: unfavoritedArticle });
+      const article = await promise;
+      expect(article.favorited).toBe(false);
+      expect(article.favoritesCount).toBe(4);
     });
   });
 });
diff --git a/src/app/features/article/services/articles.service.ts b/src/app/features/article/services/articles.service.ts
index c4b816b98..2c2418b01 100644
--- a/src/app/features/article/services/articles.service.ts
+++ b/src/app/features/article/services/articles.service.ts
@@ -14,8 +14,10 @@ export class ArticlesService {
     let params = new HttpParams();
 
     Object.keys(config.filters).forEach(key => {
-      // @ts-ignore
-      params = params.set(key, config.filters[key]);
+      const value = config.filters[key as keyof typeof config.filters];
+      if (value !== undefined) {
+        params = params.set(key, value.toString());
+      }
     });
 
     return this.http.get<{ articles: Article[]; articlesCount: number }>(
@@ -48,7 +50,7 @@ export class ArticlesService {
     return this.http.post<{ article: Article }>(`/articles/${slug}/favorite`, {}).pipe(map(data => data.article));
   }
 
-  unfavorite(slug: string): Observable<void> {
-    return this.http.delete<void>(`/articles/${slug}/favorite`);
+  unfavorite(slug: string): Observable<Article> {
+    return this.http.delete<{ article: Article }>(`/articles/${slug}/favorite`).pipe(map(data => data.article));
   }
 }