diff --git a/htdocs/core/boxes/box_graph_invoices_permonth.php b/htdocs/core/boxes/box_graph_invoices_permonth.php
index c7d1e01b2a1..94244fc95c4 100644
--- a/htdocs/core/boxes/box_graph_invoices_permonth.php
+++ b/htdocs/core/boxes/box_graph_invoices_permonth.php
@@ -131,7 +131,7 @@ class box_graph_invoices_permonth extends ModeleBoxes
 			if (empty($endyear)) {
 				$endyear = $nowarray['year'];
 			}
-			$startyear = $endyear - (!getDolGlobalString('MAIN_NB_OF_YEAR_IN_WIDGET_GRAPH') ? 2 : ($conf->global->MAIN_NB_OF_YEAR_IN_WIDGET_GRAPH - 1));
+			$startyear = $endyear - (getDolGlobalString('MAIN_NB_OF_YEAR_IN_WIDGET_GRAPH') ? ($conf->global->MAIN_NB_OF_YEAR_IN_WIDGET_GRAPH - 1) : 2);	// Default is 3 years
 
 			$mode = 'customer';
 			$WIDTH = (($shownb && $showtot) || !empty($conf->dol_optimize_smallscreen)) ? '256' : '320';