diff --git a/lightningd/pay.c b/lightningd/pay.c
index c0545ad14..4d511160a 100644
--- a/lightningd/pay.c
+++ b/lightningd/pay.c
@@ -482,6 +482,9 @@ void payment_failed(struct lightningd *ld, const struct htlc_out *hout,
 					  PAYMENT_FAILED, NULL);
 		return;
 	}
+#else
+	assert(payment);
+	assert(payment->route_channels);
 #endif
 
 	/* This gives more details than a generic failure message */
diff --git a/lightningd/peer_htlcs.c b/lightningd/peer_htlcs.c
index 3d691e37c..c03c9d4cb 100644
--- a/lightningd/peer_htlcs.c
+++ b/lightningd/peer_htlcs.c
@@ -860,8 +860,8 @@ void onchain_failed_our_htlc(const struct channel *channel,
 	struct lightningd *ld = channel->peer->ld;
 	struct htlc_out *hout = find_htlc_out_by_ripemd(channel, &htlc->ripemd);
 
-	/* Don't fail twice! */
-	if (hout->failuremsg || hout->failcode)
+	/* Don't fail twice (or if already succeeded)! */
+	if (hout->failuremsg || hout->failcode || hout->preimage)
 		return;
 
 	hout->failcode = WIRE_PERMANENT_CHANNEL_FAILURE;