diff --git a/lightningd/dual_open_control.c b/lightningd/dual_open_control.c
index 5ae8add2f..dc74e7eac 100644
--- a/lightningd/dual_open_control.c
+++ b/lightningd/dual_open_control.c
@@ -3107,6 +3107,7 @@ static struct command_result *json_openchannel_init(struct command *cmd,
 	}
 
 	if (ctype &&
+	    !cmd->ld->dev_any_channel_type &&
 	    !channel_type_accept(tmpctx,
 				 ctype->features,
 				 cmd->ld->our_features)) {
@@ -4042,7 +4043,8 @@ bool peer_start_dualopend(struct peer *peer,
 				    &channel->local_basepoints,
 				    &channel->local_funding_pubkey,
 				    channel->minimum_depth,
-				    peer->ld->config.require_confirmed_inputs);
+				    peer->ld->config.require_confirmed_inputs,
+				    peer->ld->dev_any_channel_type);
 	subd_send_msg(channel->owner, take(msg));
 	return true;
 }
diff --git a/lightningd/lightningd.c b/lightningd/lightningd.c
index 861fb8c8d..3919c678e 100644
--- a/lightningd/lightningd.c
+++ b/lightningd/lightningd.c
@@ -144,6 +144,7 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	ld->dev_ignore_modern_onion = false;
 	ld->dev_disable_commit = -1;
 	ld->dev_no_ping_timer = false;
+	ld->dev_any_channel_type = false;
 
 	/*~ This is a CCAN list: an embedded double-linked list.  It's not
 	 * really typesafe, but relies on convention to access the contents.
diff --git a/lightningd/lightningd.h b/lightningd/lightningd.h
index b2de15072..f823f59e7 100644
--- a/lightningd/lightningd.h
+++ b/lightningd/lightningd.h
@@ -337,6 +337,9 @@ struct lightningd {
 	/* Tell channeld not to worry about pings. */
 	bool dev_no_ping_timer;
 
+	/* Tell openingd/dualopend to accept all, allow sending any. */
+	bool dev_any_channel_type;
+
 	/* tor support */
 	struct wireaddr *proxyaddr;
 	bool always_use_proxy;
diff --git a/lightningd/opening_control.c b/lightningd/opening_control.c
index a7fc10eb2..6015ac2c6 100644
--- a/lightningd/opening_control.c
+++ b/lightningd/opening_control.c
@@ -981,7 +981,8 @@ bool peer_start_openingd(struct peer *peer, struct peer_fd *peer_fd)
 				   uc->minimum_depth,
 				   minrate, maxrate,
 				   peer->ld->dev_force_tmp_channel_id,
-				   peer->ld->config.allowdustreserve);
+				   peer->ld->config.allowdustreserve,
+				   peer->ld->dev_any_channel_type);
 	subd_send_msg(uc->open_daemon, take(msg));
 	return true;
 }
@@ -1171,6 +1172,7 @@ static struct command_result *json_fundchannel_start(struct command *cmd,
 		return command_param_failed();
 
 	if (ctype &&
+	    !cmd->ld->dev_any_channel_type &&
 	    !channel_type_accept(tmpctx,
 				 ctype->features,
 				 cmd->ld->our_features)) {
diff --git a/lightningd/options.c b/lightningd/options.c
index 417e801e1..80d110412 100644
--- a/lightningd/options.c
+++ b/lightningd/options.c
@@ -903,6 +903,10 @@ static void dev_register_opts(struct lightningd *ld)
 		       opt_set_bool_arg, opt_show_bool,
 		       &ld->config.allowdustreserve,
 		       "If true, we allow the `fundchannel` RPC command and the `openchannel` plugin hook to set a reserve that is below the dust limit.");
+	clnopt_noarg("--dev-any-channel-type", OPT_DEV,
+		     opt_set_bool,
+		     &ld->dev_any_channel_type,
+		     "Allow sending any channel type, and accept any");
 }
 
 static const struct config testnet_config = {
diff --git a/openingd/dualopend.c b/openingd/dualopend.c
index ac0bc06f0..6e8d45605 100644
--- a/openingd/dualopend.c
+++ b/openingd/dualopend.c
@@ -226,6 +226,8 @@ struct state {
 
 	/* Does this negotation require confirmed inputs? */
 	bool require_confirmed_inputs[NUM_SIDES];
+
+	bool dev_accept_any_channel_type;
 };
 
 /* psbt_changeset_get_next - Get next message to send
@@ -2424,11 +2426,18 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 					    open_tlv->channel_type,
 					    state->our_features);
 		if (!state->channel_type) {
-			negotiation_failed(state,
-					   "Did not support channel_type %s",
-					   fmt_featurebits(tmpctx,
-							   open_tlv->channel_type));
-			return;
+			if (state->dev_accept_any_channel_type) {
+				status_unusual("dev-any-channel-type: accepting %s",
+					       fmt_featurebits(tmpctx,
+							       open_tlv->channel_type));
+				state->channel_type = channel_type_from(state, open_tlv->channel_type);
+			} else {
+				negotiation_failed(state,
+						   "Did not support channel_type %s",
+						   fmt_featurebits(tmpctx,
+								   open_tlv->channel_type));
+				return;
+			}
 		}
 	} else
 		state->channel_type
@@ -4372,7 +4381,8 @@ int main(int argc, char *argv[])
 				    &state->our_points,
 				    &state->our_funding_pubkey,
 				    &state->minimum_depth,
-				    &state->require_confirmed_inputs[LOCAL])) {
+				    &state->require_confirmed_inputs[LOCAL],
+				    &state->dev_accept_any_channel_type)) {
 		/*~ Initially we're not associated with a channel, but
 		 * handle_peer_gossip_or_error compares this. */
 		memset(&state->channel_id, 0, sizeof(state->channel_id));
diff --git a/openingd/dualopend_wire.csv b/openingd/dualopend_wire.csv
index 92775e3ce..06996100f 100644
--- a/openingd/dualopend_wire.csv
+++ b/openingd/dualopend_wire.csv
@@ -29,6 +29,7 @@ msgdata,dualopend_init,our_funding_pubkey,pubkey,
 # Constraints in case the other end tries to open a channel.
 msgdata,dualopend_init,minimum_depth,u32,
 msgdata,dualopend_init,require_confirmed_inputs,bool,
+msgdata,dualopend_init,dev_accept_any_channel_type,bool,
 
 # master-dualopend: peer has reconnected
 msgtype,dualopend_reinit,7001
diff --git a/openingd/openingd.c b/openingd/openingd.c
index acba29718..3fd6a91d5 100644
--- a/openingd/openingd.c
+++ b/openingd/openingd.c
@@ -103,6 +103,8 @@ struct state {
 	struct amount_sat *reserve;
 
 	bool allowdustreserve;
+
+	bool dev_accept_any_channel_type;
 };
 
 /*~ If we can't agree on parameters, we fail to open the channel.
@@ -965,11 +967,18 @@ static u8 *fundee_channel(struct state *state, const u8 *open_channel_msg)
 		state->channel_type = channel_type_accept(
 		    state, open_tlvs->channel_type, state->our_features);
 		if (!state->channel_type) {
-			negotiation_failed(state,
-					   "Did not support channel_type %s",
-					   fmt_featurebits(tmpctx,
-							   open_tlvs->channel_type));
-			return NULL;
+			if (state->dev_accept_any_channel_type) {
+				status_unusual("dev-any-channel-type: accepting %s",
+					       fmt_featurebits(tmpctx,
+							       open_tlvs->channel_type));
+				state->channel_type = channel_type_from(state, open_tlvs->channel_type);
+			} else {
+				negotiation_failed(state,
+						   "Did not support channel_type %s",
+						   fmt_featurebits(tmpctx,
+								   open_tlvs->channel_type));
+				return NULL;
+			}
 		}
 	} else {
 		open_channel_had_channel_type = false;
@@ -1548,7 +1557,8 @@ int main(int argc, char *argv[])
 				    &state->minimum_depth,
 				    &state->min_feerate, &state->max_feerate,
 				    &state->dev_force_tmp_channel_id,
-				    &state->allowdustreserve))
+				    &state->allowdustreserve,
+				    &state->dev_accept_any_channel_type))
 		master_badmsg(WIRE_OPENINGD_INIT, msg);
 
 	/* 3 == peer, 4 = hsmd */
diff --git a/openingd/openingd_wire.csv b/openingd/openingd_wire.csv
index 1039ef161..65aac949f 100644
--- a/openingd/openingd_wire.csv
+++ b/openingd/openingd_wire.csv
@@ -28,6 +28,7 @@ msgdata,openingd_init,dev_temporary_channel_id,?byte,32
 # reserves? This is explicitly required by the spec for safety
 # reasons, but some implementations and users keep asking for it.
 msgdata,openingd_init,allowdustreserve,bool,
+msgdata,openingd_init,dev_accept_any_channel_type,bool,
 
 # Openingd->master: they offered channel, should we continue?
 msgtype,openingd_got_offer,6005
diff --git a/tests/test_opening.py b/tests/test_opening.py
index bb573147c..7bc4a01fd 100644
--- a/tests/test_opening.py
+++ b/tests/test_opening.py
@@ -2636,6 +2636,25 @@ def test_opening_explicit_channel_type(node_factory, bitcoind):
     with pytest.raises(RpcError, match=r'channel_type not supported'):
         l1.rpc.openchannel_init(l3.info['id'], FUNDAMOUNT - 1000, psbt, channel_type=[STATIC_REMOTEKEY, ANCHORS_OLD])
 
+    # l1 will try, with dev-any-channel-type, l2 will reject.
+    l1.stop()
+    l1.daemon.opts['dev-any-channel-type'] = None
+    l1.start()
+    l1.connect(l2)
+
+    with pytest.raises(RpcError, match=r'They sent ERROR .*: You gave bad parameters: Did not support channel_type 12,20'):
+        l1.rpc.fundchannel_start(l2.info['id'], FUNDAMOUNT, channel_type=[STATIC_REMOTEKEY, ANCHORS_OLD])
+    
+    # Now make l2 accept it!
+    l2.stop()
+    l2.daemon.opts['dev-any-channel-type'] = None
+    l2.start()
+    l1.connect(l2)
+
+    l1.rpc.fundchannel_start(l2.info['id'], FUNDAMOUNT, channel_type=[STATIC_REMOTEKEY, ANCHORS_OLD])
+    # FIXME: Check type is actually correct!
+    l1.rpc.fundchannel_cancel(l2.info['id'])
+
     l1.rpc.unreserveinputs(psbt)
 
     # Works with fundchannel / multifundchannel
@@ -2646,5 +2665,6 @@ def test_opening_explicit_channel_type(node_factory, bitcoind):
     bitcoind.generate_block(1, wait_for_mempool=1)
     wait_for(lambda: len(l1.rpc.listfunds()['outputs']) == 1)
 
+    l1.connect(l3)
     # FIXME: Check type is actually correct!
     l1.rpc.fundchannel(l3.info['id'], FUNDAMOUNT // 3, channel_type=[STATIC_REMOTEKEY])