diff --git a/party.py b/party.py
index 1169942884..9a8f842f31 100644
--- a/party.py
+++ b/party.py
@@ -168,7 +168,7 @@ class Party(ModelSQL, ModelView):
             'GROUP BY l.party '
             'HAVING (SUM((COALESCE(l.debit, 0) - COALESCE(l.credit, 0))) '
                 + clause[1] + ' %s)',
-            [code] + today_value + [company_id] + [Decimal(clause[2])])
+            [code] + today_value + [company_id] + [Decimal(clause[2] or 0)])
         return [('id', 'in', [x[0] for x in cursor.fetchall()])]
 
 Party()