diff --git a/example/example/app/models.py b/example/example/app/models.py
index 91f312a..e4f6504 100644
--- a/example/example/app/models.py
+++ b/example/example/app/models.py
@@ -20,7 +20,7 @@ from multiselectfield import MultiSelectField
 
 CATEGORY_CHOICES = (
     (1, 'Handbooks and manuals by discipline'),
-    (2, 'Business books2'),
+    (2, 'Business books'),
     (3, 'Books of literary criticism'),
     (4, 'Books about literary theory'),
     (5, 'Books about literature')
diff --git a/example/example/app/tests.py b/example/example/app/tests.py
index 37e8f91..962402e 100644
--- a/example/example/app/tests.py
+++ b/example/example/app/tests.py
@@ -36,12 +36,12 @@ class MultiSelectTestCase(TestCase):
             form.save()
 
     def test_object(self):
-        book = Book.objects.all()[0]
+        book = Book.objects.get(id=1)
         self.assertEqual(book.get_tags_display(), 'Sex, Work, Happy')
         self.assertEqual(book.get_categories_display(), 'Handbooks and manuals by discipline, Books of literary criticism, Books about literature')
 
     def test_validate(self):
-        book = Book.objects.all()[0]
+        book = Book.objects.get(id=1)
         Book._meta.get_field_by_name('tags')[0].clean(['sex', 'work'], book)
         try:
             Book._meta.get_field_by_name('tags')[0].clean(['sex1', 'work'], book)
@@ -60,3 +60,8 @@ class MultiSelectTestCase(TestCase):
             raise AssertionError()
         except ValidationError:
             pass
+
+    def test_serializer(self):
+        book = Book.objects.get(id=1)
+        self.assertEqual(Book._meta.get_field_by_name('tags')[0].value_to_string(book), 'sex,work,happy')
+        self.assertEqual(Book._meta.get_field_by_name('categories')[0].value_to_string(book), '1,3,5')