diff --git a/htdocs/core/class/commondocgenerator.class.php b/htdocs/core/class/commondocgenerator.class.php
index 6d1a31a1677..2f5a6df1449 100644
--- a/htdocs/core/class/commondocgenerator.class.php
+++ b/htdocs/core/class/commondocgenerator.class.php
@@ -744,8 +744,8 @@ abstract class CommonDocGenerator
 			'line_localtax2_rate' => vatrate($line->localtax1_tx),
 			'line_up' => price2num($line->subprice),
 			'line_up_locale' => price($line->subprice, 0, $outputlangs),
-			'line_total_up' => price2num($line->subprice * $line->qty),
-			'line_total_up_locale' => price($line->subprice * $line->qty, 0, $outputlangs),
+			'line_total_up' => price2num($line->subprice * (float) $line->qty),
+			'line_total_up_locale' => price($line->subprice * (float) $line->qty, 0, $outputlangs),
 			'line_qty' => $line->qty,
 			'line_discount_percent' => ($line->remise_percent ? $line->remise_percent.'%' : ''),
 			'line_price_ht' => price2num($line->total_ht),