diff --git a/src/Faker/ORM/Doctrine/Populator.php b/src/Faker/ORM/Doctrine/Populator.php
index 59e50041..b1877216 100644
--- a/src/Faker/ORM/Doctrine/Populator.php
+++ b/src/Faker/ORM/Doctrine/Populator.php
@@ -31,6 +31,9 @@ class Populator
     public function addEntity($entity, $number, $customColumnFormatters = array(), $customModifiers = array(), $generateId = false)
     {
         if (!$entity instanceof \Faker\ORM\Doctrine\EntityPopulator) {
+            if (null === $this->manager) {              
+                throw new \InvalidArgumentException("No entity manager passed to Doctrine Populator.");
+            }
             $entity = new \Faker\ORM\Doctrine\EntityPopulator($this->manager->getClassMetadata($entity));
         }
         $entity->setColumnFormatters($entity->guessColumnFormatters($this->generator));