diff --git a/git_trace2_event_log.py b/git_trace2_event_log.py
index dfbded15..fe34092a 100644
--- a/git_trace2_event_log.py
+++ b/git_trace2_event_log.py
@@ -92,7 +92,7 @@ class EventLog(object):
   def _AddVersionEvent(self):
     """Adds a 'version' event at the beginning of current log."""
     version_event = self._CreateEventDict('version')
-    version_event['evt'] = 2
+    version_event['evt'] = "2"
     version_event['exe'] = RepoSourceVersion()
     self._log.insert(0, version_event)
 
diff --git a/tests/test_git_trace2_event_log.py b/tests/test_git_trace2_event_log.py
index 686802ea..8fb38dbe 100644
--- a/tests/test_git_trace2_event_log.py
+++ b/tests/test_git_trace2_event_log.py
@@ -95,6 +95,8 @@ class EventLogTestCase(unittest.TestCase):
     # Check for 'version' event specific fields.
     self.assertIn('evt', version_event)
     self.assertIn('exe', version_event)
+    # Verify "evt" version field is a string.
+    self.assertIsInstance(version_event['evt'], str)
 
   def test_start_event(self):
     """Test and validate 'start' event data is valid.