diff --git a/lightning/src/ln/functional_test_utils.rs b/lightning/src/ln/functional_test_utils.rs
index de0b4c7d4bb..50bbb9fdcea 100644
--- a/lightning/src/ln/functional_test_utils.rs
+++ b/lightning/src/ln/functional_test_utils.rs
@@ -3193,6 +3193,10 @@ pub fn fail_payment<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_path: &
 }
 
 pub fn create_chanmon_cfgs(node_count: usize) -> Vec<TestChanMonCfg> {
+	create_chanmon_cfgs_with_params(node_count, false)
+}
+
+pub fn create_chanmon_cfgs_with_params(node_count: usize, legacy_channel_keys_derivation: bool) -> Vec<TestChanMonCfg> {
 	let mut chan_mon_cfgs = Vec::new();
 	for i in 0..node_count {
 		let tx_broadcaster = test_utils::TestBroadcaster::new(Network::Testnet);
@@ -3201,7 +3205,8 @@ pub fn create_chanmon_cfgs(node_count: usize) -> Vec<TestChanMonCfg> {
 		let logger = test_utils::TestLogger::with_id(format!("node {}", i));
 		let persister = test_utils::TestPersister::new();
 		let seed = [i as u8; 32];
-		let keys_manager = test_utils::TestKeysInterface::new(&seed, Network::Testnet);
+		let mut keys_manager = test_utils::TestKeysInterface::new(&seed, Network::Testnet);
+		keys_manager.legacy_channel_keys_derivation = legacy_channel_keys_derivation;
 		let scorer = RwLock::new(test_utils::TestScorer::new());
 
 		chan_mon_cfgs.push(TestChanMonCfg { tx_broadcaster, fee_estimator, chain_source, logger, persister, keys_manager, scorer });
diff --git a/lightning/src/ln/monitor_tests.rs b/lightning/src/ln/monitor_tests.rs
index 4aad8f569fc..2d36c74e245 100644
--- a/lightning/src/ln/monitor_tests.rs
+++ b/lightning/src/ln/monitor_tests.rs
@@ -2242,8 +2242,9 @@ fn test_claimable_balance_correct_while_payment_pending() {
 
 fn do_test_restored_packages_retry(check_old_monitor_retries_after_upgrade: bool) {
 	// Tests that we'll retry packages that were previously timelocked after we've restored them.
-	let chanmon_cfgs = create_chanmon_cfgs(2);
-	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let chanmon_cfgs = create_chanmon_cfgs_with_params(2, true);
+	let mut node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+
 	let persister;
 	let new_chain_monitor;
 
diff --git a/lightning/src/util/test_utils.rs b/lightning/src/util/test_utils.rs
index 122d7f0af48..229e97e1c63 100644
--- a/lightning/src/util/test_utils.rs
+++ b/lightning/src/util/test_utils.rs
@@ -1240,6 +1240,7 @@ pub struct TestKeysInterface {
 	enforcement_states: Mutex<HashMap<[u8;32], Arc<Mutex<EnforcementState>>>>,
 	expectations: Mutex<Option<VecDeque<OnGetShutdownScriptpubkey>>>,
 	pub unavailable_signers_ops: Mutex<HashMap<[u8; 32], HashSet<SignerOp>>>,
+	pub legacy_channel_keys_derivation: bool,
 }
 
 impl EntropySource for TestKeysInterface {
@@ -1292,7 +1293,11 @@ impl SignerProvider for TestKeysInterface {
 	type TaprootSigner = TestChannelSigner;
 
 	fn generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
-		self.backing.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id)
+		let mut channel_keys_id = self.backing.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id);
+		if self.legacy_channel_keys_derivation {
+			channel_keys_id[0] = 0;
+		}
+		channel_keys_id
 	}
 
 	fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> TestChannelSigner {
@@ -1344,6 +1349,7 @@ impl TestKeysInterface {
 			enforcement_states: Mutex::new(new_hash_map()),
 			expectations: Mutex::new(None),
 			unavailable_signers_ops: Mutex::new(new_hash_map()),
+			legacy_channel_keys_derivation: false,
 		}
 	}