diff --git a/src/hb-ms-feature-ranges.hh b/src/hb-ms-feature-ranges.hh
index 46a20c91e..f7649ab76 100644
--- a/src/hb-ms-feature-ranges.hh
+++ b/src/hb-ms-feature-ranges.hh
@@ -30,6 +30,9 @@
 
 #include "hb.hh"
 
+/* Variations of this code exist in hb-coretext.cc as well
+ * as hb-aat-map.cc... */
+
 typedef struct hb_ms_feature_t {
   uint32_t tag_le;
   uint32_t value;