diff --git a/pyotlss.py b/pyotlss.py
index b9550ac2d..43cccfda5 100755
--- a/pyotlss.py
+++ b/pyotlss.py
@@ -386,7 +386,8 @@ def subset_glyphs (self, glyphs):
 		setattr (self, c.RuleSetCount, len (rss))
 		return bool (rss)
 	elif self.Format == 2:
-		# TODO Renumber classes then prune rules
+		# TODO Renumber classes then prune rules that can't apply
+		# But then I first need to find fonts that use this type.  D'oh!
 		return self.Coverage.subset_glyphs (glyphs) and \
 		       all (x.subset_glyphs (glyphs) for x in c.ContextSequence (self, self.Format))
 	elif self.Format == 3: