diff --git a/crates/consensus/src/transaction/legacy.rs b/crates/consensus/src/transaction/legacy.rs
index c39abfbf186..7de6515df79 100644
--- a/crates/consensus/src/transaction/legacy.rs
+++ b/crates/consensus/src/transaction/legacy.rs
@@ -250,6 +250,7 @@ impl SignableTransaction<Signature> for TxLegacy {
     }
 
     fn into_signed(self, signature: Signature) -> Signed<Self> {
+        debug_assert_eq!(signature.v().chain_id(), self.chain_id);
         let mut buf = Vec::with_capacity(self.encoded_len_with_signature(&signature));
         self.encode_with_signature_fields(&signature, &mut buf);
         let hash = keccak256(&buf);