diff --git a/htdocs/admin/ihm.php b/htdocs/admin/ihm.php
index c2a1013be62..382355e4c4f 100644
--- a/htdocs/admin/ihm.php
+++ b/htdocs/admin/ihm.php
@@ -187,7 +187,7 @@ if (isset($_GET["action"]) && $_GET["action"] == 'edit')	// Edit
     // First day for weeks
     $var=!$var;
     print '<tr '.$bc[$var].'><td width="35%">'.$langs->trans("WeekStartOnDay").'</td><td>';
-    print $html->select_dayofweek((isset($conf->global->MAIN_START_WEEK)?$conf->global->MAIN_START_WEEK:''),'MAIN_START_WEEK',0);
+    print $html->select_dayofweek((isset($conf->global->MAIN_START_WEEK)?$conf->global->MAIN_START_WEEK:'1'),'MAIN_START_WEEK',0);
     print '</td>';
 	print '<td width="20">&nbsp;</td>';
 	print '</tr>';
@@ -346,7 +346,7 @@ else	// Show
 	// First day for weeks
     $var=!$var;
     print '<tr '.$bc[$var].'><td width="35%">'.$langs->trans("WeekStartOnDay").'</td><td>';
-    print $langs->trans("Day".(isset($conf->global->MAIN_START_WEEK)?$conf->global->MAIN_START_WEEK:'0'));
+    print $langs->trans("Day".(isset($conf->global->MAIN_START_WEEK)?$conf->global->MAIN_START_WEEK:'1'));
     print '</td>';
 	print '<td width="20">&nbsp;</td>';
 	print '</tr>';
diff --git a/htdocs/comm/action/index.php b/htdocs/comm/action/index.php
index 2b69a2d7a4e..ece88d094ff 100644
--- a/htdocs/comm/action/index.php
+++ b/htdocs/comm/action/index.php
@@ -443,7 +443,7 @@ if ($_GET["action"] != 'show_day')		// View by month
 	$i=0;
 	while ($i < 7)
 	{
-		echo '  <td align="center">'.$langs->trans("Day".(($i+$conf->global->MAIN_START_WEEK) % 7))."</td>\n";
+		echo '  <td align="center">'.$langs->trans("Day".(($i+(isset($conf->global->MAIN_START_WEEK)?$conf->global->MAIN_START_WEEK:1)) % 7))."</td>\n";
 		$i++;
 	}
 	echo " </tr>\n";