diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index b6ec022dc14..515dcbba2d2 100644
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -1987,10 +1987,8 @@ impl Writeable for OutboundOnionPayload {
 				// We need to update [`ln::outbound_payment::RecipientOnionFields::with_custom_tlvs`]
 				// to reject any reserved types in the experimental range if new ones are ever
 				// standardized.
-				let preimage = if let Some(ref preimage) = keysend_preimage {
-					Some((5482373484, preimage.encode()))
-				} else { None };
-				let mut custom_tlvs: Vec<&(u64, Vec<u8>)> = custom_tlvs.iter().chain(preimage.iter()).collect();
+				let keysend_tlv = keysend_preimage.map(|preimage| (5482373484, preimage.encode()));
+				let mut custom_tlvs: Vec<&(u64, Vec<u8>)> = custom_tlvs.iter().chain(keysend_tlv.iter()).collect();
 				custom_tlvs.sort_unstable_by_key(|(typ, _)| *typ);
 				_encode_varint_length_prefixed_tlv!(w, {
 					(2, HighZeroBytesDroppedBigSize(*amt_msat), required),
diff --git a/lightning/src/ln/outbound_payment.rs b/lightning/src/ln/outbound_payment.rs
index 9c8d6645873..bb974dc20e5 100644
--- a/lightning/src/ln/outbound_payment.rs
+++ b/lightning/src/ln/outbound_payment.rs
@@ -515,9 +515,9 @@ impl RecipientOnionFields {
 		let tlvs = &mut self.custom_tlvs;
 		let further_tlvs = &mut further_htlc_fields.custom_tlvs;
 
-		let even_tlvs: Vec<&(u64, Vec<u8>)> = tlvs.iter().filter(|(typ, _)| *typ % 2 == 0).collect();
-		let further_even_tlvs: Vec<&(u64, Vec<u8>)> = further_tlvs.iter().filter(|(typ, _)| *typ % 2 == 0).collect();
-		if even_tlvs != further_even_tlvs { return Err(()) }
+		let even_tlvs = tlvs.iter().filter(|(typ, _)| *typ % 2 == 0);
+		let further_even_tlvs = further_tlvs.iter().filter(|(typ, _)| *typ % 2 == 0);
+		if even_tlvs.ne(further_even_tlvs) { return Err(()) }
 
 		tlvs.retain(|tlv| further_tlvs.iter().any(|further_tlv| tlv == further_tlv));
 		further_tlvs.retain(|further_tlv| tlvs.iter().any(|tlv| tlv == further_tlv));
diff --git a/lightning/src/ln/payment_tests.rs b/lightning/src/ln/payment_tests.rs
index 01580368c6d..38089025810 100644
--- a/lightning/src/ln/payment_tests.rs
+++ b/lightning/src/ln/payment_tests.rs
@@ -3451,17 +3451,7 @@ fn do_test_custom_tlvs(spontaneous: bool, even_tlvs: bool, known_tlvs: bool) {
 	let events = nodes[1].node.get_and_clear_pending_events();
 	assert_eq!(events.len(), 1);
 	match events[0] {
-		Event::PaymentClaimable { ref purpose, amount_msat, ref onion_fields, .. } => {
-			match &purpose {
-				PaymentPurpose::InvoicePayment { payment_secret, .. } => {
-					assert_eq!(our_payment_secret, *payment_secret);
-					assert_eq!(Some(*payment_secret), onion_fields.as_ref().unwrap().payment_secret);
-				},
-				PaymentPurpose::SpontaneousPayment(payment_preimage) => {
-					assert_eq!(our_payment_preimage, *payment_preimage);
-				},
-			}
-			assert_eq!(amount_msat, amt_msat);
+		Event::PaymentClaimable { ref onion_fields, .. } => {
 			assert_eq!(onion_fields.clone().unwrap().custom_tlvs().clone(), custom_tlvs);
 		},
 		_ => panic!("Unexpected event"),
@@ -3518,26 +3508,12 @@ fn test_retry_custom_tlvs() {
 	nodes[0].node.send_payment(payment_hash, onion_fields,
 		payment_id, route_params.clone(), Retry::Attempts(1)).unwrap();
 	check_added_monitors!(nodes[0], 1); // one monitor per path
-	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
-	assert_eq!(events.len(), 1);
 
 	// Add the HTLC along the first hop.
-	let fail_path_msgs_1 = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
-	let (update_add, commitment_signed) = match fail_path_msgs_1 {
-		MessageSendEvent::UpdateHTLCs { node_id: _, updates: msgs::CommitmentUpdate {
-			ref update_add_htlcs, ref update_fulfill_htlcs, ref update_fail_htlcs,
-			ref update_fail_malformed_htlcs, ref update_fee, ref commitment_signed }
-		} => {
-			assert_eq!(update_add_htlcs.len(), 1);
-			assert!(update_fail_htlcs.is_empty());
-			assert!(update_fulfill_htlcs.is_empty());
-			assert!(update_fail_malformed_htlcs.is_empty());
-			assert!(update_fee.is_none());
-			(update_add_htlcs[0].clone(), commitment_signed.clone())
-		},
-		_ => panic!("Unexpected event"),
-	};
-	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &update_add);
+	let htlc_updates = get_htlc_update_msgs(&nodes[0], &nodes[1].node.get_our_node_id());
+	let msgs::CommitmentUpdate { update_add_htlcs, commitment_signed, .. } = htlc_updates;
+	assert_eq!(update_add_htlcs.len(), 1);
+	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &update_add_htlcs[0]);
 	commitment_signed_dance!(nodes[1], nodes[0], commitment_signed, false);
 
 	// Attempt to forward the payment and complete the path's failure.
@@ -3547,15 +3523,14 @@ fn test_retry_custom_tlvs() {
 			node_id: Some(nodes[2].node.get_our_node_id()),
 			channel_id: chan_2_id
 		}]);
-	let htlc_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
-	assert!(htlc_updates.update_add_htlcs.is_empty());
-	assert_eq!(htlc_updates.update_fail_htlcs.len(), 1);
-	assert!(htlc_updates.update_fulfill_htlcs.is_empty());
-	assert!(htlc_updates.update_fail_malformed_htlcs.is_empty());
 	check_added_monitors!(nodes[1], 1);
-	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(),
-		&htlc_updates.update_fail_htlcs[0]);
-	commitment_signed_dance!(nodes[0], nodes[1], htlc_updates.commitment_signed, false);
+
+	let htlc_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+	let msgs::CommitmentUpdate { update_fail_htlcs, commitment_signed, .. } = htlc_updates;
+	assert_eq!(update_fail_htlcs.len(), 1);
+	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &update_fail_htlcs[0]);
+	commitment_signed_dance!(nodes[0], nodes[1], commitment_signed, false);
+
 	let mut events = nodes[0].node.get_and_clear_pending_events();
 	match events[1] {
 		Event::PendingHTLCsForwardable { .. } => {},
@@ -3577,11 +3552,12 @@ fn test_retry_custom_tlvs() {
 	assert_eq!(events.len(), 1);
 	let payment_claimable = pass_along_path(&nodes[0], &[&nodes[1], &nodes[2]], 1_000_000,
 		payment_hash, Some(payment_secret), events.pop().unwrap(), true, None).unwrap();
-	let onion_fields = match payment_claimable {
-		Event::PaymentClaimable { onion_fields, .. } => onion_fields,
+	match payment_claimable {
+		Event::PaymentClaimable { onion_fields, .. } => {
+			assert_eq!(onion_fields.unwrap().custom_tlvs(), &custom_tlvs);
+		},
 		_ => panic!("Unexpected event"),
 	};
-	assert_eq!(onion_fields.unwrap().custom_tlvs(), &custom_tlvs);
 	claim_payment_along_route(&nodes[0], &[&[&nodes[1], &nodes[2]]], false, payment_preimage);
 }
 
@@ -3665,7 +3641,8 @@ fn do_test_custom_tlvs_consistency(first_tlvs: Vec<(u64, Vec<u8>)>, second_tlvs:
 	{
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 		assert_eq!(events.len(), 1);
-		pass_along_path(&nodes[0], &[&nodes[1], &nodes[3]], amt_msat, our_payment_hash, Some(our_payment_secret), events.pop().unwrap(), false, None);
+		pass_along_path(&nodes[0], &[&nodes[1], &nodes[3]], amt_msat, our_payment_hash,
+			Some(our_payment_secret), events.pop().unwrap(), false, None);
 	}
 	assert!(nodes[3].node.get_and_clear_pending_events().is_empty());
 
@@ -3704,26 +3681,16 @@ fn do_test_custom_tlvs_consistency(first_tlvs: Vec<(u64, Vec<u8>)>, second_tlvs:
 	if let Some(expected_tlvs) = expected_receive_tlvs {
 		// Claim and match expected
 		let events = nodes[3].node.get_and_clear_pending_events();
-		println!("events: {:?}", events);
 		assert_eq!(events.len(), 1);
 		match events[0] {
-			Event::PaymentClaimable { ref purpose, amount_msat, ref onion_fields, .. } => {
-				match &purpose {
-					PaymentPurpose::InvoicePayment { payment_secret, .. } => {
-						assert_eq!(our_payment_secret, *payment_secret);
-						assert_eq!(Some(*payment_secret), onion_fields.as_ref().unwrap().payment_secret);
-					},
-					PaymentPurpose::SpontaneousPayment(payment_preimage) => {
-						assert_eq!(our_payment_preimage, *payment_preimage);
-					},
-				}
-				assert_eq!(amount_msat, amt_msat);
+			Event::PaymentClaimable { ref onion_fields, .. } => {
 				assert_eq!(onion_fields.clone().unwrap().custom_tlvs, expected_tlvs);
 			},
 			_ => panic!("Unexpected event"),
 		}
 
-		do_claim_payment_along_route(&nodes[0], &[&[&nodes[1], &nodes[3]], &[&nodes[2], &nodes[3]]], false, our_payment_preimage);
+		do_claim_payment_along_route(&nodes[0], &[&[&nodes[1], &nodes[3]], &[&nodes[2], &nodes[3]]],
+			false, our_payment_preimage);
 		expect_payment_sent(&nodes[0], our_payment_preimage, Some(Some(2000)), true);
 	} else {
 		// Expect fail back
@@ -3735,14 +3702,19 @@ fn do_test_custom_tlvs_consistency(first_tlvs: Vec<(u64, Vec<u8>)>, second_tlvs:
 		nodes[2].node.handle_update_fail_htlc(&nodes[3].node.get_our_node_id(), &fail_updates_1.update_fail_htlcs[0]);
 		commitment_signed_dance!(nodes[2], nodes[3], fail_updates_1.commitment_signed, false);
 
-		expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[2], vec![HTLCDestination::NextHopChannel { node_id: Some(nodes[3].node.get_our_node_id()), channel_id: chan_2_3.2 }]);
+		expect_pending_htlcs_forwardable_and_htlc_handling_failed!(nodes[2], vec![
+			HTLCDestination::NextHopChannel {
+				node_id: Some(nodes[3].node.get_our_node_id()),
+				channel_id: chan_2_3.2
+			}]);
 		check_added_monitors!(nodes[2], 1);
 
 		let fail_updates_2 = get_htlc_update_msgs!(nodes[2], nodes[0].node.get_our_node_id());
 		nodes[0].node.handle_update_fail_htlc(&nodes[2].node.get_our_node_id(), &fail_updates_2.update_fail_htlcs[0]);
 		commitment_signed_dance!(nodes[0], nodes[2], fail_updates_2.commitment_signed, false);
 
-		expect_payment_failed_conditions(&nodes[0], our_payment_hash, true, PaymentFailedConditions::new().mpp_parts_remain());
+		expect_payment_failed_conditions(&nodes[0], our_payment_hash, true,
+			PaymentFailedConditions::new().mpp_parts_remain());
 	}
 }
 
diff --git a/lightning/src/util/ser_macros.rs b/lightning/src/util/ser_macros.rs
index 41185b179ff..a68dae39cdc 100644
--- a/lightning/src/util/ser_macros.rs
+++ b/lightning/src/util/ser_macros.rs
@@ -143,6 +143,9 @@ macro_rules! encode_tlv_stream {
 #[macro_export]
 macro_rules! _encode_tlv_stream {
 	($stream: expr, {$(($type: expr, $field: expr, $fieldty: tt)),* $(,)*}) => { {
+		$crate::_encode_tlv_stream!($stream, { $(($type, $field, $fieldty)),* }, &[])
+	} };
+	($stream: expr, {$(($type: expr, $field: expr, $fieldty: tt)),* $(,)*}, $extra_tlvs: expr) => { {
 		#[allow(unused_imports)]
 		use $crate::{
 			ln::msgs::DecodeError,
@@ -154,6 +157,10 @@ macro_rules! _encode_tlv_stream {
 		$(
 			$crate::_encode_tlv!($stream, $type, $field, $fieldty);
 		)*
+		for tlv in $extra_tlvs {
+			let (typ, value): &(u64, Vec<u8>) = tlv;
+			$crate::_encode_tlv!($stream, *typ, *value, required_vec);
+		}
 
 		#[allow(unused_mut, unused_variables, unused_assignments)]
 		#[cfg(debug_assertions)]
@@ -162,18 +169,8 @@ macro_rules! _encode_tlv_stream {
 			$(
 				$crate::_check_encoded_tlv_order!(last_seen, $type, $fieldty);
 			)*
-		}
-	} };
-	($stream: expr, $tlvs: expr) => { {
-		for tlv in $tlvs {
-			let (typ, value): &&(u64, Vec<u8>) = tlv;
-			$crate::_encode_tlv!($stream, *typ, *value, required_vec);
-		}
-
-		#[cfg(debug_assertions)] {
-			let mut last_seen: Option<u64> = None;
-			for tlv in $tlvs {
-				let (typ, _): &&(u64, Vec<u8>) = tlv;
+			for tlv in $extra_tlvs {
+				let (typ, _): &(u64, Vec<u8>) = tlv;
 				$crate::_check_encoded_tlv_order!(last_seen, *typ, required_vec);
 			}
 		}
@@ -246,14 +243,13 @@ macro_rules! _encode_varint_length_prefixed_tlv {
 				$crate::_get_varint_length_prefixed_tlv_length!(len, $type, $field, $fieldty);
 			)*
 			for tlv in $extra_tlvs {
-				let (typ, value): &&(u64, Vec<u8>) = tlv;
+				let (typ, value): &(u64, Vec<u8>) = tlv;
 				$crate::_get_varint_length_prefixed_tlv_length!(len, *typ, *value, required_vec);
 			}
 			len.0
 		};
 		BigSize(len as u64).write($stream)?;
-		$crate::_encode_tlv_stream!($stream, { $(($type, $field, $fieldty)),* });
-		$crate::_encode_tlv_stream!($stream, $extra_tlvs);
+		$crate::_encode_tlv_stream!($stream, { $(($type, $field, $fieldty)),* }, $extra_tlvs);
 	} };
 }