diff --git a/slave/buildslave/commands/mtn.py b/slave/buildslave/commands/mtn.py
index <HASH>..<HASH> 100644
--- a/slave/buildslave/commands/mtn.py
+++ b/slave/buildslave/commands/mtn.py
@@ -182,4 +182,4 @@ class Monotone(SourceBaseCommand):
         d = c.start()
         d.addCallback(self._abandonOnFailure)
         d.addCallback(_parse)
-
+        return d
Return the deferred from Mtn.parseGotRevision

Without this, any error in parseGotRevision is silently dropped.