diff --git a/htdocs/core/lib/date.lib.php b/htdocs/core/lib/date.lib.php
index 9aaf0771d44..03223a7b65a 100644
--- a/htdocs/core/lib/date.lib.php
+++ b/htdocs/core/lib/date.lib.php
@@ -169,7 +169,7 @@ function dol_time_plus_duree($time, $duration_value, $duration_unit, $ruleforend
 	} else {
 		$date->add($interval);
 	}
-	//Change the behavior of PHP over data-interval when the result of this function is Feb 29 (non-leap years), 30 or Feb 31 (php returns March 1, 2 or 3 respectively)
+	//Change the behavior of PHP over data-interval when the result of this function is Feb 29 (non-leap years), 30 or Feb 31 (so php returns March 1, 2 or 3 respectively)
 	if ($ruleforendofmonth == 1 && $duration_unit == 'm') {
 		$timeyear = dol_print_date($time, '%Y');
 		$timemonth = dol_print_date($time, '%m');