diff --git a/addons/stock_account/models/stock_move.py b/addons/stock_account/models/stock_move.py
index 735e982995411ab83eee33a863f9b472e6cfc64a..13fd99da58c4a8428788d9571b1e1a24b55a92c6 100644
--- a/addons/stock_account/models/stock_move.py
+++ b/addons/stock_account/models/stock_move.py
@@ -19,7 +19,7 @@ class StockMove(models.Model):
     account_move_ids = fields.One2many('account.move', 'stock_move_id')
     stock_valuation_layer_ids = fields.One2many('stock.valuation.layer', 'stock_move_id')
     analytic_account_line_id = fields.Many2one(
-        'account.analytic.line', copy=False, index=True)
+        'account.analytic.line', copy=False, index='btree_not_null')
 
     def _filter_anglo_saxon_moves(self, product):
         return self.filtered(lambda m: m.product_id.id == product.id)