diff --git a/src/Symfony/Bridge/Doctrine/PropertyInfo/DoctrineExtractor.php b/src/Symfony/Bridge/Doctrine/PropertyInfo/DoctrineExtractor.php
index 5446887abf..aba31792f9 100644
--- a/src/Symfony/Bridge/Doctrine/PropertyInfo/DoctrineExtractor.php
+++ b/src/Symfony/Bridge/Doctrine/PropertyInfo/DoctrineExtractor.php
@@ -88,7 +88,8 @@ class DoctrineExtractor implements PropertyListExtractorInterface, PropertyTypeE
 
                 if (isset($associationMapping['indexBy'])) {
                     $indexProperty = $associationMapping['indexBy'];
-                    $typeOfField = $metadata->getTypeOfField($indexProperty);
+                    $subMetadata = $this->classMetadataFactory->getMetadataFor($associationMapping['targetEntity']);
+                    $typeOfField = $subMetadata->getTypeOfField($indexProperty);
 
                     $collectionKeyType = $this->getPhpType($typeOfField);
                 }
diff --git a/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineDummy.php b/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineDummy.php
index e6d9155704..ad3b7b9227 100644
--- a/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineDummy.php
+++ b/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineDummy.php
@@ -41,7 +41,7 @@ class DoctrineDummy
     public $bar;
 
     /**
-     * @ManyToMany(targetEntity="DoctrineRelation", indexBy="guid")
+     * @ManyToMany(targetEntity="DoctrineRelation", indexBy="rguid")
      */
     protected $indexedBar;
 
diff --git a/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineRelation.php b/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineRelation.php
index 23f64d829e..6e94e028fa 100644
--- a/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineRelation.php
+++ b/src/Symfony/Bridge/Doctrine/Tests/PropertyInfo/Fixtures/DoctrineRelation.php
@@ -31,5 +31,5 @@ class DoctrineRelation
     /**
      * @Column(type="guid")
      */
-    protected $guid;
+    protected $rguid;
 }