diff --git a/cryptarchia/messages.abnf b/cryptarchia/messages.abnf
index b749146..94aa013 100644
--- a/cryptarchia/messages.abnf
+++ b/cryptarchia/messages.abnf
@@ -9,7 +9,8 @@ CONTENT-SIZE      = U32
 BLOCK-DATE        = BLOCK-SLOT
 BLOCK-SLOT        = U64
 PARENT-ID         = HEADER-ID
-MOCK-LEADER-PROOF = COMMITMENT NULLIFIER COMMITMENT
+MOCK-LEADER-PROOF = COMMITMENT NULLIFIER EVOLVE-COMMITMENT
+EVOLVE-COMMITMENT = COMMITMENT
 
 ; ------------ CONTENT --------------------
 CONTENT          = *OCTET