diff --git a/kippo/core/ttylog.py b/kippo/core/ttylog.py
index 61c398f..db83973 100644
--- a/kippo/core/ttylog.py
+++ b/kippo/core/ttylog.py
@@ -9,20 +9,20 @@ OP_OPEN, OP_CLOSE, OP_WRITE, OP_EXEC = 1, 2, 3, 4
 DIR_READ, DIR_WRITE = 1, 2
 
 def ttylog_write(logfile, len, direction, stamp, data = None):
-    f = file(logfile, 'a')
+    f = file(logfile, 'ab')
     sec, usec = int(stamp), int(1000000 * (stamp - int(stamp)))
     f.write(struct.pack('iLiiLL', 3, 0, len, direction, sec, usec))
     f.write(data)
     f.close()
 
 def ttylog_open(logfile, stamp):
-    f = file(logfile, 'a')
+    f = file(logfile, 'ab')
     sec, usec = int(stamp), int(1000000 * (stamp - int(stamp)))
     f.write(struct.pack('iLiiLL', 1, 0, 0, 0, sec, usec))
     f.close()
 
 def ttylog_close(logfile, stamp):
-    f = file(logfile, 'a')
+    f = file(logfile, 'ab')
     sec, usec = int(stamp), int(1000000 * (stamp - int(stamp)))
     f.write(struct.pack('iLiiLL', 2, 0, 0, 0, sec, usec))
     f.close()