diff --git a/party.py b/party.py
index 2f8d88faf0..aa653c084d 100644
--- a/party.py
+++ b/party.py
@@ -60,6 +60,9 @@ class Party(OSV):
                 'receivable_today', 'payable_today'):
             raise Exception('Bad argument')
 
+        if not ids:
+            return {}
+
         for i in ids:
             res[i] = Decimal('0.0')