diff --git a/sale.py b/sale.py
index 22c5328ed9..f2b4793973 100644
--- a/sale.py
+++ b/sale.py
@@ -96,7 +96,7 @@ class SaleLine:
             if field.startswith('analytic_account_'):
                 if vals[field]:
                     selection_vals.setdefault('accounts', [])
-                    selection_vals['accounts'].append(('add', vals[field]))
+                    selection_vals['accounts'].append(('add', [vals[field]]))
                 del vals[field]
         if vals.get('analytic_accounts'):
             Selection.write([Selection(vals['analytic_accounts'])],