diff --git a/testsample.py b/testsample.py
index 74acdaa..98ae969 100644
--- a/testsample.py
+++ b/testsample.py
@@ -7,6 +7,7 @@ import StringIO
 
 class TestMilter(sample.sampleMilter):
 
+  _protocol = 0
   def __init__(self):
     self.logfp = open("test/milter.log","a")