diff --git a/lib/Doctrine/ORM/Persisters/ManyToManyPersister.php b/lib/Doctrine/ORM/Persisters/ManyToManyPersister.php
index daef03774..c7dc08dff 100644
--- a/lib/Doctrine/ORM/Persisters/ManyToManyPersister.php
+++ b/lib/Doctrine/ORM/Persisters/ManyToManyPersister.php
@@ -180,7 +180,7 @@ class ManyToManyPersister extends AbstractCollectionPersister
         // Composite identifier
         $sourceClass = $this->_em->getClassMetadata(get_class($mapping->getOwner()));
 
-        foreach ($mapping['relationToSourceKeyColumns'] as $relColumn => $srcColumn) {
+        foreach ($mapping['relationToSourceKeyColumns'] as $srcColumn) {
             $params[] = $identifier[$sourceClass->fieldNames[$srcColumn]];
         }