diff --git a/src/hb-ot-shape-complex-arabic-fallback.hh b/src/hb-ot-shape-complex-arabic-fallback.hh
index 2d8488e15..d488885dc 100644
--- a/src/hb-ot-shape-complex-arabic-fallback.hh
+++ b/src/hb-ot-shape-complex-arabic-fallback.hh
@@ -33,6 +33,7 @@
 #include "hb-ot-layout-gsub-table.hh"
 
 
+/* Features ordered the same as the entries in shaping_table rows. */
 static const hb_tag_t arabic_fallback_features[] =
 {
   HB_TAG('i','n','i','t'),