diff --git a/classes/module/ModuleGraph.php b/classes/module/ModuleGraph.php
index 0d659dca0..6ba3b5566 100644
--- a/classes/module/ModuleGraph.php
+++ b/classes/module/ModuleGraph.php
@@ -28,6 +28,9 @@ abstract class ModuleGraphCore extends Module
 {
     protected $_employee;
 
+    /** @var string CSV data */
+    protected $_csv;
+
     /** @var array of integers graph data */
     protected $_values = array();