diff --git a/app/Models/VersionGantt.php b/app/Models/VersionGantt.php
index 236bff2..0784bbe 100644
--- a/app/Models/VersionGantt.php
+++ b/app/Models/VersionGantt.php
@@ -41,6 +41,10 @@ class VersionGantt extends Model
 
     public function updateActDuration(){
       $daysOff = explode(',', $this->config_dayoff);
+      if (in_array('0', $daysOff)) {
+        $key = array_search('0', $daysOff, false);
+        $daysOff[$key] = '7';
+      }
       $activities = Activity::where('version_gantt_id', $this->id)->get();
       foreach ($activities as $value) {
         $startDate = new DateTime($value->start_date);