--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -5130,20 +5130,21 @@ class SqueakyCleanLogger(object):
     def __init__(self):
         self.errors = []
 
     def debug(self, msg, *args, **kwargs):
         pass
     info = debug
 
     def warning(self, msg, *args, **kwargs):
-        if msg == "%s:%d: Rule '%s' defined, but not used":
+        if msg == "%s:%d: Rule %r defined, but not used" or \
+           msg == "%s:%d: Rule '%s' defined, but not used":
             # Munge things so we don't have to hardcode filenames and
             # line numbers in our whitelist.
-            whitelistmsg = "Rule '%s' defined, but not used"
+            whitelistmsg = "Rule %r defined, but not used"
             whitelistargs = args[2:]
         else:
             whitelistmsg = msg
             whitelistargs = args
         if (whitelistmsg % whitelistargs) not in SqueakyCleanLogger.errorWhitelist:
             self.errors.append(msg % args)
     error = warning