diff --git a/lightning/src/ln/outbound_payment.rs b/lightning/src/ln/outbound_payment.rs
index ef20ef99e82..0931f04572a 100644
--- a/lightning/src/ln/outbound_payment.rs
+++ b/lightning/src/ln/outbound_payment.rs
@@ -294,6 +294,11 @@ impl PendingOutboundPayment {
 					// `ChannelManager` after transitioning from this state to `Retryable` prior to shutdown.
 					// Therefore, we need to move this payment to `Retryable` now to avoid double-paying if
 					// the recipient sends a duplicate invoice.
+					//
+					// We leave many fields as `None` if they are only used for retries, since we'll never
+					// retry on startup. See this method's callsite in `ChannelManager::read`, but this
+					// mirrors the behavior if an HTLC in a monitor is entirely missing from
+					// `OutboundPayments`.
 					*self = Self::Retryable {
 						retry_strategy: None,
 						attempts: PaymentAttempts::new(),