diff --git a/repo b/repo
index f12354a..7769565 100755
--- a/repo
+++ b/repo
@@ -462,7 +462,7 @@
     try:
       r = urllib.request.urlopen(url)
     except urllib.error.HTTPError as e:
-      if e.code in [401, 403, 404]:
+      if e.code in [401, 403, 404, 501]:
         return False
       _print('fatal: Cannot get %s' % url, file=sys.stderr)
       _print('fatal: HTTP error %s' % e.code, file=sys.stderr)