diff --git a/lib/Doctrine/ORM/Tools/EntityGenerator.php b/lib/Doctrine/ORM/Tools/EntityGenerator.php
index f81f63bb3..36ebc52ca 100644
--- a/lib/Doctrine/ORM/Tools/EntityGenerator.php
+++ b/lib/Doctrine/ORM/Tools/EntityGenerator.php
@@ -316,7 +316,7 @@ public function <methodName>()
      */
     public function setFieldVisibility($visibility)
     {
-        if ($visibility != 'private' && $visibility != 'protected') {
+        if ($visibility !== EntityGenerator::FIELD_VISIBLE_PRIVATE && $visibility !== EntityGenerator::FIELD_VISIBLE_PROTECTED) {
             throw new \InvalidArgumentException('Invalid provided visibilty (only private and protected are allowed): ' . $visibility);
         }