diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index 457017647..1eb52fcfb 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -115,7 +115,7 @@ struct hb_closure_context_t :
 	  return true;
       }
 
-      hb_set_clear (done_lookups_glyph_set->get (lookup_index));
+      done_lookups_glyph_set->get (lookup_index)->clear ();
     }
 
     hb_set_t *covered_glyph_set = done_lookups_glyph_set->get (lookup_index);