diff --git a/include/jpgraph/jpgraph_pie.php b/include/jpgraph/jpgraph_pie.php
index c79d30fa..cea4d107 100644
--- a/include/jpgraph/jpgraph_pie.php
+++ b/include/jpgraph/jpgraph_pie.php
@@ -31,7 +31,7 @@ class PiePlot {
     protected $labels=null, $legends=null;
     protected $csimtargets=null,$csimwintargets=null;  // Array of targets for CSIM
     protected $csimareas='';  // Generated CSIM text
-    protected $csimalts=null;  // ALT tags for corresponding target
+    protected $csimalts=array();  // ALT tags for corresponding target
     protected $data=null;
     public $title;
     protected $startangle=0;