diff --git a/htdocs/compta/facture.php b/htdocs/compta/facture.php
index 34ed1383e14..a5e4334228d 100644
--- a/htdocs/compta/facture.php
+++ b/htdocs/compta/facture.php
@@ -771,7 +771,7 @@ if (empty($reshook))
 	                        $line->fk_parent_line = $fk_parent_line;
 
 	                        $line->subprice =-$line->subprice; // invert price for object
-	                        $line->pa_ht = -$line->pa_ht;
+	                        $line->pa_ht = $line->pa_ht;
 	                        $line->total_ht=-$line->total_ht;
 	                        $line->total_tva=-$line->total_tva;
 	                        $line->total_ttc=-$line->total_ttc;
diff --git a/htdocs/contrat/class/contrat.class.php b/htdocs/contrat/class/contrat.class.php
index e4bee39c39e..65ea14219d1 100644
--- a/htdocs/contrat/class/contrat.class.php
+++ b/htdocs/contrat/class/contrat.class.php
@@ -1601,8 +1601,8 @@ class Contrat extends CommonObject
 				if (empty($conf->global->MAIN_EXTRAFIELDS_DISABLED) && is_array($array_options) && count($array_options)>0) // For avoid conflicts if trigger used
 				{
 					$contractline = new ContratLigne($this->db);
-					$contractline->array_options=$array_option;
-					$contractline->id= $this->db->last_insert_id(MAIN_DB_PREFIX.$contractline->table_element);
+					$contractline->array_options=$array_options;
+					$contractline->id= $rowid;
 					$result=$contractline->insertExtraFields();
 					if ($result < 0)
 					{
diff --git a/htdocs/core/lib/date.lib.php b/htdocs/core/lib/date.lib.php
index b06baaa9288..e08b6c24de5 100644
--- a/htdocs/core/lib/date.lib.php
+++ b/htdocs/core/lib/date.lib.php
@@ -2,6 +2,7 @@
 /* Copyright (C) 2004-2011 Laurent Destailleur  <eldy@users.sourceforge.net>
  * Copyright (C) 2005-2011 Regis Houssin        <regis.houssin@capnetworks.com>
  * Copyright (C) 2011-2015 Juanjo Menent        <jmenent@2byte.es>
+ * Copyright (C) 2017      Ferran Marcet        <fmarcet@2byte.es>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -407,7 +408,7 @@ function dol_get_next_week($day, $week, $month, $year)
 {
 	$tmparray = dol_get_first_day_week($day, $month, $year);
 
-	$time=dol_mktime(12,0,0,$month,$tmparray['first_day'],$year,1,0);
+	$time=dol_mktime(12,0,0,$tmparray['first_month'],$tmparray['first_day'],$tmparray['first_year'],1,0);
 	$time+=24*60*60*7;
 	$tmparray=dol_getdate($time,true);
 
diff --git a/htdocs/install/mysql/migration/3.8.0-3.9.0.sql b/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
index 86d2549a8bc..88ba07cc24b 100755
--- a/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
+++ b/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
@@ -611,3 +611,7 @@ INSERT INTO llx_c_tva(rowid,fk_pays,taux,recuperableonly,note,active) VALUES (14
 -- VMYSQL4.1 ALTER TABLE llx_c_type_resource CHANGE COLUMN rowid rowid integer NOT NULL AUTO_INCREMENT;
 
 ALTER TABLE llx_import_model MODIFY COLUMN type varchar(50);
+
+-- Negative buying prices
+
+UPDATE llx_facturedet SET buy_price_ht = ABS(buy_price_ht)