diff --git a/common/gossmap.c b/common/gossmap.c
index bec5dea27eae..a61947bc5636 100644
--- a/common/gossmap.c
+++ b/common/gossmap.c
@@ -1249,6 +1249,8 @@ void gossmap_chan_get_update_details(const struct gossmap *map,
 	const size_t htlc_maximum_off = fee_prop_off + 4;
 
 	assert(gossmap_chan_set(chan, dir));
+	/* Not allowed on local updates! */
+	assert(chan->cann_off < map->map_size);
 
 	if (timestamp)
 		*timestamp = map_be32(map, timestamp_off);
diff --git a/common/gossmap.h b/common/gossmap.h
index b173c9bd5515..edaec7415f6d 100644
--- a/common/gossmap.h
+++ b/common/gossmap.h
@@ -155,7 +155,7 @@ u8 *gossmap_node_get_features(const tal_t *ctx,
 			      const struct gossmap_node *n);
 
 /* Returns details from channel_update (must be gossmap_chan_set, and
- * does not work for local_updatechan! */
+ * does not work for local_updatechan)! */
 void gossmap_chan_get_update_details(const struct gossmap *map,
 				     const struct gossmap_chan *chan,
 				     int dir,
diff --git a/plugins/topology.c b/plugins/topology.c
index d4e29628c6b0..dd934c02f386 100644
--- a/plugins/topology.c
+++ b/plugins/topology.c
@@ -266,14 +266,27 @@ static void json_add_halfchan(struct json_stream *response,
 		json_add_num(response, "direction", dir);
 		json_add_bool(response, "public", !c->private);
 
-		gossmap_chan_get_update_details(gossmap, c, dir,
-						&timestamp,
-						&message_flags,
-						&channel_flags,
-						&fee_base_msat,
-						&fee_proportional_millionths,
-						&htlc_minimum_msat,
-						&htlc_maximum_msat);
+		if (c->private) {
+			/* Local additions don't have a channel_update
+			 * in gossmap.  This is deprecated anyway, but
+			 * fill in values from entry we added. */
+			timestamp = time_now().ts.tv_sec;
+			message_flags = (ROUTING_OPT_HTLC_MAX_MSAT|ROUTING_OPT_DONT_FORWARD);
+			channel_flags = node_id_idx(&node_id[dir], &node_id[!dir]);
+			fee_base_msat = c->half[dir].base_fee;
+			fee_proportional_millionths = c->half[dir].proportional_fee;
+			htlc_minimum_msat = amount_msat(fp16_to_u64(c->half[dir].htlc_min));
+			htlc_maximum_msat = amount_msat(fp16_to_u64(c->half[dir].htlc_max));
+		} else {
+			gossmap_chan_get_update_details(gossmap, c, dir,
+							&timestamp,
+							&message_flags,
+							&channel_flags,
+							&fee_base_msat,
+							&fee_proportional_millionths,
+							&htlc_minimum_msat,
+							&htlc_maximum_msat);
+		}
 
 		json_add_amount_sat_msat(response, "amount_msat", capacity);
 		json_add_num(response, "message_flags", message_flags);
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 8410539ee7c4..87414c066171 100644
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -3785,6 +3785,7 @@ def test_upgrade_statickey_onchaind(node_factory, executor, bitcoind):
 
     bitcoind.generate_block(100, wait_for_mempool=txid)
     # This works even if they disconnect and listpeerchannels() is empty:
+    wait_for(lambda: l1.rpc.listpeerchannels()['channels'] == [])
     wait_for(lambda: l2.rpc.listpeerchannels()['channels'] == [])
 
     # TEST 2: Cheat from post-upgrade.
@@ -3817,6 +3818,7 @@ def test_upgrade_statickey_onchaind(node_factory, executor, bitcoind):
 
     bitcoind.generate_block(100, wait_for_mempool=txid)
     # This works even if they disconnect and listpeers() is empty:
+    wait_for(lambda: len(l1.rpc.listpeerchannels()['channels']) == 0)
     wait_for(lambda: len(l2.rpc.listpeerchannels()['channels']) == 0)
 
     # TEST 3: Unilateral close from pre-upgrade
@@ -3852,6 +3854,7 @@ def test_upgrade_statickey_onchaind(node_factory, executor, bitcoind):
     bitcoind.generate_block(100, wait_for_mempool=txid)
 
     # This works even if they disconnect and listpeerchannels() is empty:
+    wait_for(lambda: len(l1.rpc.listpeerchannels()['channels']) == 0)
     wait_for(lambda: len(l2.rpc.listpeerchannels()['channels']) == 0)
 
     # TEST 4: Unilateral close from post-upgrade