diff --git a/src/hb-ot-maxp-table.hh b/src/hb-ot-maxp-table.hh
index e0e6bd787..10bd592e8 100644
--- a/src/hb-ot-maxp-table.hh
+++ b/src/hb-ot-maxp-table.hh
@@ -105,7 +105,7 @@ struct maxp
     }
     maxp *maxp_prime = (maxp *) hb_blob_get_data (maxp_prime_blob, nullptr);
 
-    maxp_prime->set_num_glyphs (plan->num_glyphs);
+    maxp_prime->set_num_glyphs (plan->num_output_glyphs ());
     if (plan->drop_hints)
       drop_hint_fields (plan, maxp_prime);