diff --git a/src/dispextern.h b/src/dispextern.h
index bba96ba8171..2740364427d 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1537,6 +1537,7 @@ enum display_element_type
 
 enum prop_idx
 {
+  AUTO_COMPOSED_PROP_IDX,
   FONTIFIED_PROP_IDX,
   FACE_PROP_IDX,
   INVISIBLE_PROP_IDX,