diff --git a/master/buildbot/steps/source/git.py b/master/buildbot/steps/source/git.py
index 97801956f9e..48748ae1a1d 100644
--- a/master/buildbot/steps/source/git.py
+++ b/master/buildbot/steps/source/git.py
@@ -577,6 +577,9 @@ def checkWithPathExists(exists):
             d = self.runCommand(cmd)
 
             def checkWithListdir(_):
+                if 'files' not in cmd.updates:
+                    # no files - directory doesn't exist
+                    return "clone"
                 files = cmd.updates['files'][0]
                 if '.git' in files:
                     return "update"