diff --git a/htdocs/mrp/mo_agenda.php b/htdocs/mrp/mo_agenda.php
index a4f043489f4..60ac81e20cd 100644
--- a/htdocs/mrp/mo_agenda.php
+++ b/htdocs/mrp/mo_agenda.php
@@ -209,7 +209,7 @@ if ($object->id > 0) {
 		if (get_class($objthirdparty) == 'Societe') {
 			$out .= '&socid='.$objthirdparty->id;
 		}
-		$out .= (!empty($objcon->id) ? '&contactid='.$objcon->id : '').'&backtopage='.$_SERVER["PHP_SELF"].'?id='.$object->id.'&percentage=-1';
+		$out .= (!empty($objcon->id) ? '&contactid='.$objcon->id : '').'&backtopage='.urlencode($_SERVER["PHP_SELF"].'?id='.$object->id).'&percentage=-1';
 		//$out.=$langs->trans("AddAnAction").' ';
 		//$out.=img_picto($langs->trans("AddAnAction"),'filenew');
 		//$out.="</a>";