diff --git a/common/gossmap.c b/common/gossmap.c
index 277e87d99..918fb913a 100644
--- a/common/gossmap.c
+++ b/common/gossmap.c
@@ -398,6 +398,7 @@ static struct gossmap_chan *add_channel(struct gossmap *map,
 	const size_t feature_len_off = 2 + (64 + 64 + 64 + 64);
 	size_t feature_len;
 	size_t plus_scid_off;
+	struct short_channel_id scid;
 	struct node_id node_id[2];
 	struct gossmap_node *n[2];
 	struct gossmap_chan *chan;
@@ -409,6 +410,16 @@ static struct gossmap_chan *add_channel(struct gossmap *map,
 	map_nodeid(map, cannounce_off + plus_scid_off + 8, &node_id[0]);
 	map_nodeid(map, cannounce_off + plus_scid_off + 8 + PUBKEY_CMPR_LEN, &node_id[1]);
 
+	/* We can have a channel upgrade from private->public, but
+	 * that's the only time we get duplicates */
+	scid.u64 = map_be64(map, cannounce_off + plus_scid_off);
+	chan = gossmap_find_chan(map, &scid);
+	if (chan) {
+		assert(chan->private);
+		assert(!private);
+		gossmap_remove_chan(map, chan);
+	}
+
 	/* We carefully map pointers to indexes, since new_node can move them! */
 	n[0] = gossmap_find_node(map, &node_id[0]);
 	if (n[0])
diff --git a/common/test/run-route-specific.c b/common/test/run-route-specific.c
index 01d12f94f..3a1488c49 100644
--- a/common/test/run-route-specific.c
+++ b/common/test/run-route-specific.c
@@ -215,9 +215,9 @@ int main(int argc, char *argv[])
 		       0, 10, 5);
 
 	/* {'active': True, 'short_id': '6990:2:1/0', 'fee_per_kw': 10, 'delay': 5, 'message_flags': 0, 'channel_flags': 0, 'destination': '02ea622d5c8d6143f15ed3ce1d501dd0d3d09d3b1c83a44d0034949f8a9ab60f06', 'source': '0230ad0e74ea03976b28fda587bb75bdd357a1938af4424156a18265167f5e40ae', 'last_update': 1504064344}, */
-	add_connection(store_fd, &b, &c, "6990x2x1",
-		       AMOUNT_MSAT(100), AMOUNT_MSAT(1000),
-		       0, 10, 5);
+	update_connection(store_fd, &b, &c, "6990x2x1",
+			  AMOUNT_MSAT(100), AMOUNT_MSAT(1000),
+			  0, 10, 5, false);
 
 	/* {'active': True, 'short_id': '6989:2:1/1', 'fee_per_kw': 10, 'delay': 5, 'message_flags': 0, 'channel_flags': 1, 'destination': '0230ad0e74ea03976b28fda587bb75bdd357a1938af4424156a18265167f5e40ae', 'source': '03c173897878996287a8100469f954dd820fcd8941daed91c327f168f3329be0bf', 'last_update': 1504064344}]} */
 	update_connection(store_fd, &a, &b, "6989x2x1",