diff --git a/library/Director/Import/PurgeStrategy/PurgeStrategy.php b/library/Director/Import/PurgeStrategy/PurgeStrategy.php
index 436d7a3e..ffbe14fa 100644
--- a/library/Director/Import/PurgeStrategy/PurgeStrategy.php
+++ b/library/Director/Import/PurgeStrategy/PurgeStrategy.php
@@ -18,7 +18,7 @@ abstract class PurgeStrategy
         return $this->rule;
     }
 
-    abstract function listObjectsToPurge();
+    abstract public function listObjectsToPurge();
 
     /**
      * @return PurgeStrategy