diff --git a/gossipd/gossipd.c b/gossipd/gossipd.c
index 48903d5fb..74e46ad26 100644
--- a/gossipd/gossipd.c
+++ b/gossipd/gossipd.c
@@ -1947,55 +1947,62 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
  * marshalling the channel information for all channels into an array of
  * gossip_getchannels_entry, which lightningd converts to JSON.  Each channel
  * is represented by two half_chan; one in each direction.
- *
- * FIXME: I run a lightning node permanently under valgrind, and Christian ran
- * `listchannels` on it.  After about 15 minutes I simply rebooted.  There's
- * been some optimization since then, but blocking gossipd to marshall all the
- * channels will become in issue in future, I expect.  We may even hit the
- * 2^24 internal message limit.
  */
-static void append_half_channel(struct gossip_getchannels_entry **entries,
-				const struct chan *chan,
-				int idx)
+static struct gossip_halfchannel_entry *hc_entry(const tal_t *ctx,
+						 const struct chan *chan,
+						 int idx)
 {
-	const struct half_chan *c = &chan->half[idx];
-	struct gossip_getchannels_entry e;
-
-	/* If we've never seen a channel_update for this direction... */
-	if (!is_halfchan_defined(c))
-		return;
-
 	/* Our 'struct chan' contains two nodes: they are in pubkey_cmp order
 	 * (ie. chan->nodes[0] is the lesser pubkey) and this is the same as
 	 * the direction bit in `channel_update`s `channel_flags`.
 	 *
 	 * The halfchans are arranged so that half[0] src == nodes[0], and we
-	 * use that here.  We also avoid using libsecp256k1 to translate the
-	 * pubkeys to DER and back: that proves quite expensive, and we assume
-	 * we're on the same architecture as lightningd, so we just send them
-	 * raw in this case. */
-	e.source = chan->nodes[idx]->id;
-	e.destination = chan->nodes[!idx]->id;
-	e.sat = chan->sat;
-	e.channel_flags = c->channel_flags;
-	e.message_flags = c->message_flags;
-	e.local_disabled = chan->local_disabled;
-	e.public = is_chan_public(chan);
-	e.short_channel_id = chan->scid;
-	e.last_update_timestamp = c->last_timestamp;
-	e.base_fee_msat = c->base_fee;
-	e.fee_per_millionth = c->proportional_fee;
-	e.delay = c->delay;
+	 * use that here. */
+	const struct half_chan *c = &chan->half[idx];
+	struct gossip_halfchannel_entry *e;
 
-	tal_arr_expand(entries, e);
+	/* If we've never seen a channel_update for this direction... */
+	if (!is_halfchan_defined(c))
+		return NULL;
+
+	e = tal(ctx, struct gossip_halfchannel_entry);
+	e->channel_flags = c->channel_flags;
+	e->message_flags = c->message_flags;
+	e->last_update_timestamp = c->last_timestamp;
+	e->base_fee_msat = c->base_fee;
+	e->fee_per_millionth = c->proportional_fee;
+	e->delay = c->delay;
+
+	return e;
 }
 
-/*~ Marshal (possibly) both channel directions into entries */
-static void append_channel(struct gossip_getchannels_entry **entries,
-			   const struct chan *chan)
+/*~ Marshal (possibly) both channel directions into entries. */
+static void append_channel(const struct gossip_getchannels_entry ***entries,
+			   const struct chan *chan,
+			   const struct node_id *srcfilter)
 {
-	append_half_channel(entries, chan, 0);
-	append_half_channel(entries, chan, 1);
+	struct gossip_getchannels_entry *e = tal(*entries, struct gossip_getchannels_entry);
+
+	e->node[0] = chan->nodes[0]->id;
+	e->node[1] = chan->nodes[1]->id;
+	e->sat = chan->sat;
+	e->local_disabled = chan->local_disabled;
+	e->public = is_chan_public(chan);
+	e->short_channel_id = chan->scid;
+	if (!srcfilter || node_id_eq(&e->node[0], srcfilter))
+		e->e[0] = hc_entry(*entries, chan, 0);
+	else
+		e->e[0] = NULL;
+	if (!srcfilter || node_id_eq(&e->node[1], srcfilter))
+		e->e[1] = hc_entry(*entries, chan, 1);
+	else
+		e->e[1] = NULL;
+
+	/* We choose not to tell lightningd about channels with no updates,
+	 * as they're unusable and can't be represented in the listchannels
+	 * JSON output we use anyway. */
+	if (e->e[0] || e->e[1])
+		tal_arr_expand(entries, e);
 }
 
 /*~ This is where lightningd asks for all channels we know about. */
@@ -2004,7 +2011,7 @@ static struct io_plan *getchannels_req(struct io_conn *conn,
 				       const u8 *msg)
 {
 	u8 *out;
-	struct gossip_getchannels_entry *entries;
+	const struct gossip_getchannels_entry **entries;
 	struct chan *chan;
 	struct short_channel_id *scid;
 	struct node_id *source;
@@ -2013,12 +2020,12 @@ static struct io_plan *getchannels_req(struct io_conn *conn,
 	if (!fromwire_gossip_getchannels_request(msg, msg, &scid, &source))
 		master_badmsg(WIRE_GOSSIP_GETCHANNELS_REQUEST, msg);
 
-	entries = tal_arr(tmpctx, struct gossip_getchannels_entry, 0);
+	entries = tal_arr(tmpctx, const struct gossip_getchannels_entry *, 0);
 	/* They can ask about a particular channel by short_channel_id */
 	if (scid) {
 		chan = get_channel(daemon->rstate, scid);
 		if (chan)
-			append_channel(&entries, chan);
+			append_channel(&entries, chan, NULL);
 	} else if (source) {
 		struct node *s = get_node(daemon->rstate, source);
 		if (s) {
@@ -2026,9 +2033,7 @@ static struct io_plan *getchannels_req(struct io_conn *conn,
 			struct chan *c;
 
 			for (c = first_chan(s, &i); c; c = next_chan(s, &i)) {
-				append_half_channel(&entries,
-						    c,
-						    !half_chan_to(s, c));
+				append_channel(&entries, c, source);
 			}
 		}
 	} else {
@@ -2039,7 +2044,7 @@ static struct io_plan *getchannels_req(struct io_conn *conn,
 		for (chan = uintmap_first(&daemon->rstate->chanmap, &idx);
 		     chan;
 		     chan = uintmap_after(&daemon->rstate->chanmap, &idx)) {
-			append_channel(&entries, chan);
+			append_channel(&entries, chan, NULL);
 		}
 	}
 
diff --git a/lightningd/gossip_control.c b/lightningd/gossip_control.c
index 910a1aced..462e7cbb6 100644
--- a/lightningd/gossip_control.c
+++ b/lightningd/gossip_control.c
@@ -367,12 +367,43 @@ static const struct json_command getroute_command = {
 };
 AUTODATA(json_command, &getroute_command);
 
+static void json_add_halfchan(struct json_stream *response,
+			      const struct gossip_getchannels_entry *e,
+			      int idx)
+{
+	const struct gossip_halfchannel_entry *he = e->e[idx];
+	if (!he)
+		return;
+
+	json_object_start(response, NULL);
+	json_add_node_id(response, "source", &e->node[idx]);
+	json_add_node_id(response, "destination", &e->node[!idx]);
+	json_add_short_channel_id(response, "short_channel_id",
+				  &e->short_channel_id);
+	json_add_bool(response, "public", e->public);
+	json_add_amount_sat(response, e->sat,
+			    "satoshis", "amount_msat");
+	json_add_num(response, "message_flags", he->message_flags);
+	json_add_num(response, "channel_flags", he->channel_flags);
+	/* Prior to spec v0891374d47ddffa64c5a2e6ad151247e3d6b7a59, these two were a single u16 field */
+	if (deprecated_apis)
+		json_add_num(response, "flags", ((u16)he->message_flags << 8) | he->channel_flags);
+	json_add_bool(response, "active",
+		      !(he->channel_flags & ROUTING_FLAGS_DISABLED)
+		      && !e->local_disabled);
+	json_add_num(response, "last_update", he->last_update_timestamp);
+	json_add_num(response, "base_fee_millisatoshi", he->base_fee_msat);
+	json_add_num(response, "fee_per_millionth", he->fee_per_millionth);
+	json_add_num(response, "delay", he->delay);
+	json_object_end(response);
+}
+
 /* Called upon receiving a getchannels_reply from `gossipd` */
 static void json_listchannels_reply(struct subd *gossip UNUSED, const u8 *reply,
 				   const int *fds UNUSED, struct command *cmd)
 {
 	size_t i;
-	struct gossip_getchannels_entry *entries;
+	struct gossip_getchannels_entry **entries;
 	struct json_stream *response;
 
 	if (!fromwire_gossip_getchannels_reply(reply, reply, &entries)) {
@@ -385,33 +416,8 @@ static void json_listchannels_reply(struct subd *gossip UNUSED, const u8 *reply,
 	json_object_start(response, NULL);
 	json_array_start(response, "channels");
 	for (i = 0; i < tal_count(entries); i++) {
-		json_object_start(response, NULL);
-		json_add_node_id(response, "source",
-					   &entries[i].source);
-		json_add_node_id(response, "destination",
-					   &entries[i].destination);
-		json_add_string(response, "short_channel_id",
-				type_to_string(reply, struct short_channel_id,
-					       &entries[i].short_channel_id));
-		json_add_bool(response, "public", entries[i].public);
-		json_add_amount_sat(response, entries[i].sat,
-				    "satoshis", "amount_msat");
-		json_add_num(response, "message_flags", entries[i].message_flags);
-		json_add_num(response, "channel_flags", entries[i].channel_flags);
-		/* Prior to spec v0891374d47ddffa64c5a2e6ad151247e3d6b7a59, these two were a single u16 field */
-		if (deprecated_apis)
-			json_add_num(response, "flags", ((u16)entries[i].message_flags << 8) | entries[i].channel_flags);
-		json_add_bool(response, "active",
-			      !(entries[i].channel_flags & ROUTING_FLAGS_DISABLED)
-			      && !entries[i].local_disabled);
-		json_add_num(response, "last_update",
-			     entries[i].last_update_timestamp);
-		json_add_num(response, "base_fee_millisatoshi",
-			     entries[i].base_fee_msat);
-		json_add_num(response, "fee_per_millionth",
-			     entries[i].fee_per_millionth);
-		json_add_num(response, "delay", entries[i].delay);
-		json_object_end(response);
+		json_add_halfchan(response, entries[i], 0);
+		json_add_halfchan(response, entries[i], 1);
 	}
 	json_array_end(response);
 	json_object_end(response);
diff --git a/lightningd/gossip_msg.c b/lightningd/gossip_msg.c
index 2b6404606..7150ef9dd 100644
--- a/lightningd/gossip_msg.c
+++ b/lightningd/gossip_msg.c
@@ -96,38 +96,76 @@ void towire_route_info(u8 **pptr, const struct route_info *entry)
 	towire_u16(pptr, entry->cltv_expiry_delta);
 }
 
-void fromwire_gossip_getchannels_entry(const u8 **pptr, size_t *max,
-				       struct gossip_getchannels_entry *entry)
+static void fromwire_gossip_halfchannel_entry(const u8 **pptr, size_t *max,
+					      struct gossip_halfchannel_entry *entry)
 {
-	fromwire_short_channel_id(pptr, max, &entry->short_channel_id);
-	fromwire_node_id(pptr, max, &entry->source);
-	fromwire_node_id(pptr, max, &entry->destination);
-	entry->sat = fromwire_amount_sat(pptr, max);
 	entry->message_flags = fromwire_u8(pptr, max);
 	entry->channel_flags = fromwire_u8(pptr, max);
-	entry->public = fromwire_bool(pptr, max);
-	entry->local_disabled = fromwire_bool(pptr, max);
 	entry->last_update_timestamp = fromwire_u32(pptr, max);
+	entry->delay = fromwire_u32(pptr, max);
 	entry->base_fee_msat = fromwire_u32(pptr, max);
 	entry->fee_per_millionth = fromwire_u32(pptr, max);
-	entry->delay = fromwire_u32(pptr, max);
+}
+
+struct gossip_getchannels_entry *
+fromwire_gossip_getchannels_entry(const tal_t *ctx,
+				  const u8 **pptr, size_t *max)
+{
+	struct gossip_getchannels_entry *entry;
+
+	entry= tal(ctx, struct gossip_getchannels_entry);
+	fromwire_node_id(pptr, max, &entry->node[0]);
+	fromwire_node_id(pptr, max, &entry->node[1]);
+	entry->sat = fromwire_amount_sat(pptr, max);
+	fromwire_short_channel_id(pptr, max, &entry->short_channel_id);
+	entry->public = fromwire_bool(pptr, max);
+	entry->local_disabled = fromwire_bool(pptr, max);
+
+	if (fromwire_bool(pptr, max)) {
+		entry->e[0] = tal(entry, struct gossip_halfchannel_entry);
+		fromwire_gossip_halfchannel_entry(pptr, max, entry->e[0]);
+	} else
+		entry->e[0] = NULL;
+	if (fromwire_bool(pptr, max)) {
+		entry->e[1] = tal(entry, struct gossip_halfchannel_entry);
+		fromwire_gossip_halfchannel_entry(pptr, max, entry->e[1]);
+	} else
+		entry->e[1] = NULL;
+
+	return entry;
+}
+
+static void towire_gossip_halfchannel_entry(u8 **pptr,
+					    const struct gossip_halfchannel_entry *entry)
+{
+	towire_u8(pptr, entry->message_flags);
+	towire_u8(pptr, entry->channel_flags);
+	towire_u32(pptr, entry->last_update_timestamp);
+	towire_u32(pptr, entry->delay);
+	towire_u32(pptr, entry->base_fee_msat);
+	towire_u32(pptr, entry->fee_per_millionth);
 }
 
 void towire_gossip_getchannels_entry(u8 **pptr,
 				     const struct gossip_getchannels_entry *entry)
 {
-	towire_short_channel_id(pptr, &entry->short_channel_id);
-	towire_node_id(pptr, &entry->source);
-	towire_node_id(pptr, &entry->destination);
+	towire_node_id(pptr, &entry->node[0]);
+	towire_node_id(pptr, &entry->node[1]);
 	towire_amount_sat(pptr, entry->sat);
-	towire_u8(pptr, entry->message_flags);
-	towire_u8(pptr, entry->channel_flags);
+	towire_short_channel_id(pptr, &entry->short_channel_id);
 	towire_bool(pptr, entry->public);
 	towire_bool(pptr, entry->local_disabled);
-	towire_u32(pptr, entry->last_update_timestamp);
-	towire_u32(pptr, entry->base_fee_msat);
-	towire_u32(pptr, entry->fee_per_millionth);
-	towire_u32(pptr, entry->delay);
+	if (entry->e[0]) {
+		towire_bool(pptr, true);
+		towire_gossip_halfchannel_entry(pptr, entry->e[0]);
+	} else
+		towire_bool(pptr, false);
+
+	if (entry->e[1]) {
+		towire_bool(pptr, true);
+		towire_gossip_halfchannel_entry(pptr, entry->e[1]);
+	} else
+		towire_bool(pptr, false);
 }
 
 struct peer_features *
diff --git a/lightningd/gossip_msg.h b/lightningd/gossip_msg.h
index 5a62e4995..26ab7c898 100644
--- a/lightningd/gossip_msg.h
+++ b/lightningd/gossip_msg.h
@@ -20,20 +20,25 @@ struct gossip_getnodes_entry {
 	u8 color[3];
 };
 
-struct gossip_getchannels_entry {
-	struct node_id source, destination;
-	struct amount_sat sat;
-	struct short_channel_id short_channel_id;
+struct gossip_halfchannel_entry {
 	u8 message_flags;
 	u8 channel_flags;
-	bool public;
-	bool local_disabled;
 	u32 last_update_timestamp;
 	u32 delay;
 	u32 base_fee_msat;
 	u32 fee_per_millionth;
 };
 
+struct gossip_getchannels_entry {
+	struct node_id node[2];
+	struct amount_sat sat;
+	struct short_channel_id short_channel_id;
+	bool public;
+	bool local_disabled;
+	/* NULL if we haven't received an update */
+	struct gossip_halfchannel_entry *e[2];
+};
+
 struct gossip_getnodes_entry *
 fromwire_gossip_getnodes_entry(const tal_t *ctx, const u8 **pptr, size_t *max);
 void towire_gossip_getnodes_entry(u8 **pptr,
@@ -49,8 +54,9 @@ void towire_route_hop(u8 **pprt, const struct route_hop *entry);
 void fromwire_route_info(const u8 **pprt, size_t *max, struct route_info *entry);
 void towire_route_info(u8 **pprt, const struct route_info *entry);
 
-void fromwire_gossip_getchannels_entry(const u8 **pptr, size_t *max,
-				       struct gossip_getchannels_entry *entry);
+struct gossip_getchannels_entry *
+fromwire_gossip_getchannels_entry(const tal_t *ctx,
+				  const u8 **pptr, size_t *max);
 void towire_gossip_getchannels_entry(
     u8 **pptr, const struct gossip_getchannels_entry *entry);
 
diff --git a/tools/generate-wire.py b/tools/generate-wire.py
index 688cb974e..5dde18660 100755
--- a/tools/generate-wire.py
+++ b/tools/generate-wire.py
@@ -37,6 +37,7 @@ type2size = {
 varlen_structs = [
     'peer_features',
     'gossip_getnodes_entry',
+    'gossip_getchannels_entry',
     'failed_htlc',
     'utxo',
     'bitcoin_tx',
diff --git a/wire/wire_io.h b/wire/wire_io.h
index 2cdb537ee..fd6d773c3 100644
--- a/wire/wire_io.h
+++ b/wire/wire_io.h
@@ -5,9 +5,8 @@
 #include <ccan/io/io.h>
 #include <ccan/short_types/short_types.h>
 
-/* We don't allow > 64M msgs: enough for 483 64k failure msgs. */
-/* FIXME: Too big, but allows the million-channels project at 327077670 bytes */
-#define WIRE_LEN_LIMIT (1 << 29)
+/* We don't allow > 128M msgs: enough for more than 1M channels in gossip_getchannels_entry. */
+#define WIRE_LEN_LIMIT (1 << 27)
 
 typedef be32 wire_len_t;
 #define wirelen_to_cpu be32_to_cpu