diff --git a/htdocs/projet/activity/perday.php b/htdocs/projet/activity/perday.php
index 79a259f1ccc..d64d6bf0eda 100644
--- a/htdocs/projet/activity/perday.php
+++ b/htdocs/projet/activity/perday.php
@@ -602,6 +602,11 @@ $restrictviewformytask = ((!isset($conf->global->PROJECT_TIME_SHOW_TASK_NOT_ASSI
 
 // Get if user is available or not for each day
 $isavailable = array();
+
+// Assume from Monday to Friday if conf empty or badly formed
+$numstartworkingday = 1;
+$numendworkingday = 5;
+
 if (!empty($conf->global->MAIN_DEFAULT_WORKING_DAYS))
 {
 	$tmparray = explode('-', $conf->global->MAIN_DEFAULT_WORKING_DAYS);
diff --git a/htdocs/projet/activity/perweek.php b/htdocs/projet/activity/perweek.php
index 1f1bbc96336..cdfd9229d0c 100644
--- a/htdocs/projet/activity/perweek.php
+++ b/htdocs/projet/activity/perweek.php
@@ -507,6 +507,11 @@ $startday = dol_mktime(12, 0, 0, $startdayarray['first_month'], $startdayarray['
 
 // Get if user is available or not for each day
 $isavailable = array();
+
+// Assume from Monday to Friday if conf empty or badly formed
+$numstartworkingday = 1;
+$numendworkingday = 5;
+
 if (!empty($conf->global->MAIN_DEFAULT_WORKING_DAYS))
 {
 	$tmparray = explode('-', $conf->global->MAIN_DEFAULT_WORKING_DAYS);
@@ -516,7 +521,6 @@ if (!empty($conf->global->MAIN_DEFAULT_WORKING_DAYS))
 		$numendworkingday = $tmparray[1];
 	}
 }
-
 for ($idw = 0; $idw < 7; $idw++)
 {
 	$dayinloopfromfirstdaytoshow = dol_time_plus_duree($firstdaytoshow, $idw, 'd'); // $firstdaytoshow is a date with hours = 0