diff --git a/specs/light_client/merkle_proofs.md b/specs/light_client/merkle_proofs.md
index f52941118..311a4aa5c 100644
--- a/specs/light_client/merkle_proofs.md
+++ b/specs/light_client/merkle_proofs.md
@@ -1,3 +1,5 @@
+**NOTICE**: This document is a work-in-progress for researchers and implementers.
+
 ### Constants
 
 | Name | Value |