diff --git a/openingd/dualopend.c b/openingd/dualopend.c
index 5a01a43c7cd3..1638c3539c82 100644
--- a/openingd/dualopend.c
+++ b/openingd/dualopend.c
@@ -2433,7 +2433,7 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 				state->channel_type = channel_type_from(state, open_tlv->channel_type);
 			} else {
 				negotiation_failed(state,
-						   "Did not support channel_type %s",
+						   "Did not support channel_type [%s]",
 						   fmt_featurebits(tmpctx,
 								   open_tlv->channel_type));
 				return;
diff --git a/openingd/openingd.c b/openingd/openingd.c
index 3fd6a91d571a..8ebdeea38cc8 100644
--- a/openingd/openingd.c
+++ b/openingd/openingd.c
@@ -974,7 +974,7 @@ static u8 *fundee_channel(struct state *state, const u8 *open_channel_msg)
 				state->channel_type = channel_type_from(state, open_tlvs->channel_type);
 			} else {
 				negotiation_failed(state,
-						   "Did not support channel_type %s",
+						   "Did not support channel_type [%s]",
 						   fmt_featurebits(tmpctx,
 								   open_tlvs->channel_type));
 				return NULL;
diff --git a/tests/test_opening.py b/tests/test_opening.py
index 54497f7f94c5..2dd15826258d 100644
--- a/tests/test_opening.py
+++ b/tests/test_opening.py
@@ -2654,7 +2654,7 @@ def test_opening_explicit_channel_type(node_factory, bitcoind):
     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'):
+    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!