diff --git a/src/Grant/PasswordGrant.php b/src/Grant/PasswordGrant.php
index 6d98115d..f87fc6ea 100644
--- a/src/Grant/PasswordGrant.php
+++ b/src/Grant/PasswordGrant.php
@@ -77,12 +77,12 @@ class PasswordGrant extends AbstractGrant
     {
         $username = $this->getRequestParameter('username', $request);
         if (is_null($username)) {
-            throw OAuthServerException::invalidRequest('username', '`%s` parameter is missing');
+            throw OAuthServerException::invalidRequest('username');
         }
 
         $password = $this->getRequestParameter('password', $request);
         if (is_null($password)) {
-            throw OAuthServerException::invalidRequest('password', '`%s` parameter is missing');
+            throw OAuthServerException::invalidRequest('password');
         }
 
         $user = $this->userRepository->getUserEntityByUserCredentials(