diff --git a/zipline/finance/performance.py b/zipline/finance/performance.py
index d72c229d..76231d2e 100644
--- a/zipline/finance/performance.py
+++ b/zipline/finance/performance.py
@@ -114,8 +114,6 @@ Performance Period
 import logging
 import datetime
 import pytz
-import msgpack
-import pandas
 import math
 
 import zmq
diff --git a/zipline/logging.cfg b/zipline/logging.cfg
index 911d2a2a..168420ac 100644
--- a/zipline/logging.cfg
+++ b/zipline/logging.cfg
@@ -20,7 +20,7 @@ qualname=ZiplineLogger
 class=handlers.RotatingFileHandler
 level=DEBUG
 formatter=ziplineformat
-args=("/var/log/zipline/zipline.log",10*1024*1024,5)
+args=("/var/log/zipline/zipline.log",'a',10*1024*1024,5)
 propagate=1
 
 [handler_consoleHandler]