diff --git a/coordinator/src/tests/mod.rs b/coordinator/src/tests/mod.rs
index 8d760e2a..a21e73aa 100644
--- a/coordinator/src/tests/mod.rs
+++ b/coordinator/src/tests/mod.rs
@@ -1 +1 @@
-mod transaction;
+mod tributary;
diff --git a/coordinator/src/tests/transaction.rs b/coordinator/src/tests/tributary.rs
similarity index 97%
rename from coordinator/src/tests/transaction.rs
rename to coordinator/src/tests/tributary.rs
index aa6882ae..21e5b87e 100644
--- a/coordinator/src/tests/transaction.rs
+++ b/coordinator/src/tests/tributary.rs
@@ -7,7 +7,7 @@ use frost::Participant;
 
 use tributary::{ReadWrite, tests::random_signed};
 
-use crate::transaction::{SignData, Transaction};
+use crate::tributary::{SignData, Transaction};
 
 fn random_u32<R: RngCore>(rng: &mut R) -> u32 {
   u32::try_from(rng.next_u64() >> 32).unwrap()
diff --git a/coordinator/src/transaction.rs b/coordinator/src/tributary.rs
similarity index 91%
rename from coordinator/src/transaction.rs
rename to coordinator/src/tributary.rs
index cc418a79..9618bb15 100644
--- a/coordinator/src/transaction.rs
+++ b/coordinator/src/tributary.rs
@@ -1,14 +1,29 @@
 use std::{io, collections::HashMap};
 
 use blake2::{Digest, Blake2s256};
+use transcript::{Transcript, RecommendedTranscript};
 
 use frost::Participant;
 
+use serai_client::validator_sets::primitives::ValidatorSet;
+
 #[rustfmt::skip]
 use tributary::{
-  ReadWrite, Signed, TransactionError, TransactionKind, Transaction as TransactionTrait
+  ReadWrite, Signed, TransactionError, TransactionKind, Transaction as TransactionTrait,
 };
 
+pub fn genesis(serai_block: [u8; 32], set: ValidatorSet) -> [u8; 32] {
+  // Calculate the genesis for this Tributary
+  let mut genesis = RecommendedTranscript::new(b"Serai Tributary Genesis");
+  // This locks it to a specific Serai chain
+  genesis.append_message(b"serai_block", serai_block);
+  genesis.append_message(b"session", set.session.0.to_le_bytes());
+  genesis.append_message(b"network", set.network.0.to_le_bytes());
+  let genesis = genesis.challenge(b"genesis");
+  let genesis_ref: &[u8] = genesis.as_ref();
+  genesis_ref[.. 32].try_into().unwrap()
+}
+
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct SignData {
   pub plan: [u8; 32],