diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 3ac943cba..6bc964d0e 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -834,8 +834,8 @@ class UnitOfWork implements PropertyChangedListener
         $targetClass    = $this->em->getClassMetadata($assoc['targetEntity']);
 
         foreach ($unwrappedValue as $key => $entry) {
-            if (! ($entry instanceof $assoc['targetEntity']))) {
-                throw ORMInvalidArgumentException::invalidAssociation($entry);
+            if (! ($entry instanceof $targetClass->name))) {
+                throw ORMInvalidArgumentException::invalidAssociation($targetClass, $assoc, $entry);
             }
 
             $state = $this->getEntityState($entry, self::STATE_NEW);