diff --git a/htdocs/expensereport/class/expensereport.class.php b/htdocs/expensereport/class/expensereport.class.php
index b524850fdb4..a12381f1fc9 100644
--- a/htdocs/expensereport/class/expensereport.class.php
+++ b/htdocs/expensereport/class/expensereport.class.php
@@ -850,12 +850,9 @@ class ExpenseReport extends CommonObject
     {
         global $conf,$langs;
 
+        $this->oldref = $this->ref;
         $expld_car = (empty($conf->global->NDF_EXPLODE_CHAR))?"-":$conf->global->NDF_EXPLODE_CHAR;
 
-        // Sélection du numéro de ref suivant
-        $ref_next = $this->getNextNumRef();
-        $ref_number_int = ($this->ref+1)-1;
-
         // Sélection de la date de début de la NDF
         $sql = 'SELECT date_debut';
         $sql.= ' FROM '.MAIN_DB_PREFIX.$this->table_element;
@@ -864,21 +861,59 @@ class ExpenseReport extends CommonObject
         $objp = $this->db->fetch_object($result);
         $this->date_debut = $this->db->jdate($objp->date_debut);
 
-        // Création du ref_number suivant
-        if($ref_next)
+        $update_number_int = false;
+
+        // Create next ref if ref is PROVxx
+        // Rename directory if dir was a temporary ref
+        if (preg_match('/^[\(]?PROV/i', $this->ref))
         {
-            $prefix="ER";
-            if (! empty($conf->global->EXPENSE_REPORT_PREFIX)) $prefix=$conf->global->EXPENSE_REPORT_PREFIX;
-            $this->ref = strtoupper($fuser->login).$expld_car.$prefix.$this->ref.$expld_car.dol_print_date($this->date_debut,'%y%m%d');
+            // Sélection du numéro de ref suivant
+            $ref_next = $this->getNextNumRef();
+            $ref_number_int = ($this->ref+1)-1;
+            $update_number_int = true;
+            // Création du ref_number suivant
+            if($ref_next)
+            {
+                $prefix="ER";
+                if (! empty($conf->global->EXPENSE_REPORT_PREFIX)) $prefix=$conf->global->EXPENSE_REPORT_PREFIX;
+                $this->ref = strtoupper($fuser->login).$expld_car.$prefix.$this->ref.$expld_car.dol_print_date($this->date_debut,'%y%m%d');
+            }
+            require_once DOL_DOCUMENT_ROOT.'/core/lib/files.lib.php';
+            // We rename directory in order to avoid losing the attachments
+            $oldref = dol_sanitizeFileName($this->oldref);
+            $newref = dol_sanitizeFileName($this->ref);
+            $dirsource = $conf->expensereport->dir_output.'/'.$oldref;
+            $dirdest = $conf->expensereport->dir_output.'/'.$newref;
+            if (file_exists($dirsource))
+            {
+                dol_syslog(get_class($this)."::valid() rename dir ".$dirsource." into ".$dirdest);
+
+                if (@rename($dirsource, $dirdest))
+                {
+                    dol_syslog("Rename ok");
+                    // Rename docs starting with $oldref with $newref
+                    $listoffiles=dol_dir_list($conf->expensereport->dir_output.'/'.$newref, 'files', 1, '^'.preg_quote($oldref,'/'));
+                    foreach($listoffiles as $fileentry)
+                    {
+                        $dirsource=$fileentry['name'];
+                        $dirdest=preg_replace('/^'.preg_quote($oldref,'/').'/',$newref, $dirsource);
+                        $dirsource=$fileentry['path'].'/'.$dirsource;
+                        $dirdest=$fileentry['path'].'/'.$dirdest;
+                        @rename($dirsource, $dirdest);
+                    }
+                }
+            }
         }
 
         if ($this->fk_statut != 2)
         {
         	$now = dol_now();
-        	
+
             $sql = 'UPDATE '.MAIN_DB_PREFIX.$this->table_element;
-            $sql.= " SET ref = '".$this->ref."', fk_statut = 2, fk_user_valid = ".$fuser->id.", date_valid='".$this->db->idate($now)."',";
-            $sql.= " ref_number_int = ".$ref_number_int;
+            $sql.= " SET ref = '".$this->ref."', fk_statut = 2, fk_user_valid = ".$fuser->id.", date_valid='".$this->db->idate($now)."'";
+            if ($update_number_int) {
+                $sql.= ", ref_number_int = ".$ref_number_int;
+            }
             $sql.= ' WHERE rowid = '.$this->id;
 
             $resql=$this->db->query($sql);