diff --git a/htdocs/core/boxes/box_funnel_of_prospection.php b/htdocs/core/boxes/box_funnel_of_prospection.php
index 28c3b22788d..dd5bce78301 100644
--- a/htdocs/core/boxes/box_funnel_of_prospection.php
+++ b/htdocs/core/boxes/box_funnel_of_prospection.php
@@ -237,7 +237,7 @@ class box_funnel_of_prospection extends ModeleBoxes
 					$dolgraph->setBorderColor(array_values($bordercolorseries));
 					$dolgraph->setShowLegend(2);
 					if (!empty($conf->dol_optimize_smallscreen)) {
-						$px1->SetWidth(320);
+						$dolgraph->SetWidth(320);
 					}
 					$dolgraph->setShowPercent(1);
 					$dolgraph->setMirrorGraphValues(true);