diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index e6efa158b..285760274 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -552,7 +552,7 @@ hb_buffer_t::delete_glyph ()
     goto done;
   }
 
-  /* TODO We need to just merge one direction, with whichever is smaller. */
+  /* TODO We need to just merge one direction, with whichever is smaller but larger than our cluster. */
 
   if (out_len)
   {