diff --git a/Export/ExportManager.php b/Export/ExportManager.php
index 3a5e15afc..85c2b4280 100644
--- a/Export/ExportManager.php
+++ b/Export/ExportManager.php
@@ -379,7 +379,8 @@ class ExportManager
     public function &getAggregatorsApplyingOn(ExportInterface $export, array $centers = null)
     {
         if ($export instanceof ListInterface) {
-            return array();
+            
+            return;
         }
         
         foreach ($this->aggregators as $alias => $aggregator) {