diff --git a/README.md b/README.md
index aaa3d5d..4b92d3c 100644
--- a/README.md
+++ b/README.md
@@ -98,7 +98,7 @@ Test method `test_custom_error_message()`.
 
 ## Task 9. Your Own Validation Rule.
 
-In `app/Http/Controllers/ArticleController.php` file, in `store` method, the code uses `Uppercase` validation rule that you need to create with Artisan command, and fill in with the rule of "title" having first letter as uppercase.
+In `app/Http/Controllers/ArticleController.php` file, in `store` method, the code uses `Uppercase` validation rule that you need to create with Artisan command, and fill in with the rule of "title" having first letter as uppercase with the error message "The title does not start with an uppercased letter".
 
 Test method `test_custom_validation_rule()`.
 
diff --git a/app/Models/User.php b/app/Models/User.php
index 6a41429..4f83a9c 100644
--- a/app/Models/User.php
+++ b/app/Models/User.php
@@ -41,5 +41,6 @@ class User extends Authenticatable
      */
     protected $casts = [
         'email_verified_at' => 'datetime',
+        'is_admin' => 'boolean',
     ];
 }
diff --git a/tests/Feature/ValidationTest.php b/tests/Feature/ValidationTest.php
index afc187e..f5dba8b 100644
--- a/tests/Feature/ValidationTest.php
+++ b/tests/Feature/ValidationTest.php
@@ -94,7 +94,7 @@ class ValidationTest extends TestCase
 
         $user = User::where('name', $updatedUser['name'])->first();
         $this->assertNotNull($user);
-        $this->assertEquals(false, $user->is_admin);
+        $this->assertFalse($user->is_admin);
     }
 
     public function test_custom_error_message()
@@ -107,6 +107,11 @@ class ValidationTest extends TestCase
     public function test_custom_validation_rule()
     {
         $response = $this->post('articles', ['title' => 'lowercase']);
-        $response->assertSessionHasErrors('title')->assertStatus(302);
+        $response->assertSessionHasErrors([
+            'title' => 'The title does not start with an uppercased letter',
+        ])->assertStatus(302);
+
+        $response = $this->post('articles', ['title' => 'Uppercase']);
+        $response->assertStatus(200);
     }
 }