diff --git a/tests/Grant/AuthCodeGrantTest.php b/tests/Grant/AuthCodeGrantTest.php
index 5ca3c8f1..70682171 100644
--- a/tests/Grant/AuthCodeGrantTest.php
+++ b/tests/Grant/AuthCodeGrantTest.php
@@ -540,6 +540,7 @@ class AuthCodeGrantTest extends TestCase
         $client = new ClientEntity();
         $client->setIdentifier('foo');
         $client->setRedirectUri('http://foo/bar');
+        $client->setIsConfidential();
         $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
         $clientRepositoryMock->method('getClientEntity')->willReturn($client);
 
@@ -629,7 +630,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-	
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setScopeRepository($scopeRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
diff --git a/tests/Stubs/ClientEntity.php b/tests/Stubs/ClientEntity.php
index 4cb79a0c..9d34edb0 100644
--- a/tests/Stubs/ClientEntity.php
+++ b/tests/Stubs/ClientEntity.php
@@ -14,4 +14,9 @@ class ClientEntity implements ClientEntityInterface
     {
         $this->redirectUri = $uri;
     }
+
+    public function setIsConfidential()
+    {
+        $this->isConfidential = true;
+    }
 }