diff --git a/tests/Exception/OAuthServerExceptionTest.php b/tests/Exception/OAuthServerExceptionTest.php
index 7ece08032..38b86d433 100644
--- a/tests/Exception/OAuthServerExceptionTest.php
+++ b/tests/Exception/OAuthServerExceptionTest.php
@@ -137,4 +137,11 @@ public function testCanGetRedirectionUri()
 
         $this->assertSame('https://example.com/error', $exceptionWithRedirect->getRedirectUri());
     }
+
+    public function testInvalidCredentialsIsInvalidGrant()
+    {
+        $exception = OAuthServerException::invalidCredentials();
+
+        $this->assertSame('invalid_grant', $exception->getErrorType());
+    }
 }
diff --git a/tests/Grant/PasswordGrantTest.php b/tests/Grant/PasswordGrantTest.php
index 0be3d4826..b53ab2357 100644
--- a/tests/Grant/PasswordGrantTest.php
+++ b/tests/Grant/PasswordGrantTest.php
@@ -211,7 +211,7 @@ public function testRespondToRequestBadCredentials()
         $responseType = new StubResponseType();
 
         $this->expectException(\League\OAuth2\Server\Exception\OAuthServerException::class);
-        $this->expectExceptionCode(10);
+        $this->expectExceptionCode(6);
 
         $grant->respondToAccessTokenRequest($serverRequest, $responseType, new DateInterval('PT5M'));
     }