diff --git a/src/hb-ot-shape-normalize.hh b/src/hb-ot-shape-normalize.hh
index 80755f775..04f1a8009 100644
--- a/src/hb-ot-shape-normalize.hh
+++ b/src/hb-ot-shape-normalize.hh
@@ -41,7 +41,7 @@ enum hb_ot_shape_normalization_mode_t {
   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS, /* Never composes base-to-base */
   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT, /* Always fully decomposes and then recompose back */
 
-  HB_OT_SHAPE_NORMALIZATION_MODE_AUTO, /* Choose decomposed if GPOS mark feature available, compose otherwise. */
+  HB_OT_SHAPE_NORMALIZATION_MODE_AUTO, /* See hb-ot-shape-normalize.cc for logic. */
   HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT = HB_OT_SHAPE_NORMALIZATION_MODE_AUTO
 };