diff --git a/addons/account/wizard/account_report_common.py b/addons/account/wizard/account_report_common.py
index 48130b041d0..8ae425e0b15 100644
--- a/addons/account/wizard/account_report_common.py
+++ b/addons/account/wizard/account_report_common.py
@@ -71,7 +71,7 @@ class account_common_report(osv.osv_memory):
                                AND p.special = false
                                ORDER BY p.date_start ASC, p.special ASC
                                LIMIT 1) AS period_start
-                UNION
+                UNION ALL
                 SELECT * FROM (SELECT p.id
                                FROM account_period p
                                LEFT JOIN account_fiscalyear f ON (p.fiscalyear_id = f.id)