--- a/fetch_command.py
+++ b/fetch_command.py
@@ -127,9 +127,9 @@ def replay_convert_rev(hg_editor, svn, r
             hg_editor.ui.flush()
             if p[-1] == '/':
                 dirpath = p[len(rootpath):]
-                files_to_grab.update((dirpath + f for f,k in
+                files_to_grab.update([dirpath + f for f,k in
                                       svn.list_files(dirpath, r.revnum)
-                                      if k == 'f'))
+                                      if k == 'f'])
             else:
                 files_to_grab.add(p[len(rootpath):])
         hg_editor.ui.status('\nFetching files...\n')