diff --git a/addons/mrp_repair/mrp_repair.py b/addons/mrp_repair/mrp_repair.py
index 0227de401d4..d35f4780699 100644
--- a/addons/mrp_repair/mrp_repair.py
+++ b/addons/mrp_repair/mrp_repair.py
@@ -222,7 +222,7 @@ class mrp_repair(osv.osv):
         if move_id:
             move =  self.pool.get('stock.move').browse(cr, uid, move_id)
             product = self.pool.get('product.product').browse(cr, uid, prod_id)
-            limit = datetime.strptime(move.date_expected, '%Y-%m-%d %H:%M:%S') + relativedelta(months=product.warranty)
+            limit = datetime.strptime(move.date_expected, '%Y-%m-%d %H:%M:%S') + relativedelta(months=int(product.warranty))
             data['value']['guarantee_limit'] = limit.strftime('%Y-%m-%d')
             data['value']['location_id'] = move.location_dest_id.id
             data['value']['location_dest_id'] = move.location_dest_id.id