diff --git a/python/tidy.py b/python/tidy.py
index c75319f5394..0fac94240c7 100644
--- a/python/tidy.py
+++ b/python/tidy.py
@@ -413,6 +413,7 @@ def check_webidl_spec(file_name, contents):
         "//dvcs.w3.org/hg",
         "//dom.spec.whatwg.org",
         "//domparsing.spec.whatwg.org",
+        "//drafts.fxtf.org",
         "//encoding.spec.whatwg.org",
         "//html.spec.whatwg.org",
         "//url.spec.whatwg.org",