diff --git a/test/test_convert.py b/test/test_convert.py
index 2a32e51e7..fe74b0b73 100644
--- a/test/test_convert.py
+++ b/test/test_convert.py
@@ -15,6 +15,7 @@
 
 from __future__ import division, absolute_import, print_function
 
+import sys
 import re
 import os.path
 import unittest
@@ -39,7 +40,7 @@ class TestHelper(helper.TestHelper):
 
         # A Python script that copies the file and appends a tag.
         stub = os.path.join(_common.RSRC, b'convert_stub.py').decode('utf-8')
-        return u"python '{}' $source $dest {}".format(stub, tag)
+        return u"python{} '{}' $source $dest {}".format(sys.version_info.major, stub, tag)
 
     def assertFileTag(self, path, tag):  # noqa
         """Assert that the path is a file and the files content ends with `tag`.