diff --git a/bzr_exporter.py b/bzr_exporter.py
index <HASH>..<HASH> 100755
--- a/bzr_exporter.py
+++ b/bzr_exporter.py
@@ -244,7 +244,7 @@ class BzrFastExporter(object):
         # Print the commit
         git_ref = 'refs/heads/%s' % (git_branch,)
         mark = ncommits + 1
-        self.revid_to_mark[revid] = str(mark)
+        self.revid_to_mark[revid] = ':' + str(mark)
         file_cmds = self._get_filecommands(parent, revid)
         self.print_cmd(self._get_commit_command(git_ref, mark, revobj,
             file_cmds))
really put ':' in the commit mark