diff --git a/Lib/xdrlib.py b/Lib/xdrlib.py
index 901a05bfea8..2c3e3360d7c 100644
--- a/Lib/xdrlib.py
+++ b/Lib/xdrlib.py
@@ -268,7 +268,7 @@ class Unpacker:
 
 
 # test suite
-def __test():
+def _test():
     p = Packer()
     packtest = [
 	(p.pack_uint,    (9,)),
@@ -321,4 +321,4 @@ def __test():
 	count = count + 1
 
 if __name__ == '__main__':
-    __test()
+    _test()