diff --git a/master/buildbot/changes/gerritchangesource.py b/master/buildbot/changes/gerritchangesource.py
index <HASH>..<HASH> 100644
--- a/master/buildbot/changes/gerritchangesource.py
+++ b/master/buildbot/changes/gerritchangesource.py
@@ -143,6 +143,8 @@ class GerritChangeSource(base.ChangeSource):
             # eat failures..
             d.addErrback(log.err, 'error adding change from GerritChangeSource')
             return d
+        else:
+            return defer.succeed(None)
 
     def streamProcessStopped(self):
         self.process = None
always return a Deferred from GerritChangeSource.lineReceived

Fixes #<I>.