diff --git a/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt b/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
index eb1fe0f35..7868688d5 100644
--- a/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
+++ b/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
@@ -422,18 +422,18 @@ data class Commitment(
             "built remote commit number=${remoteCommit.index + 1} toLocalMsat=${spec.toLocal.toLong()} toRemoteMsat=${spec.toRemote.toLong()} htlc_in=$htlcsIn htlc_out=$htlcsOut feeratePerKw=${spec.feerate} txId=${remoteCommitTx.tx.txid} fundingTxId=$fundingTxId"
         }
 
-        val commitSig = when (spec.htlcs.size) {
-            0 -> {
+        val tlvs = buildSet {
+            if (spec.htlcs.isEmpty()) {
                 val alternativeSigs = Commitments.alternativeFeerates.map { feerate ->
                     val alternativeSpec = spec.copy(feerate = feerate)
                     val (alternativeRemoteCommitTx, _) = Commitments.makeRemoteTxs(channelKeys, commitTxNumber = remoteCommit.index + 1, params.localParams, params.remoteParams, fundingTxIndex = fundingTxIndex, remoteFundingPubKey = remoteFundingPubkey, commitInput, remotePerCommitmentPoint = remoteNextPerCommitmentPoint, alternativeSpec)
                     val alternativeSig = Transactions.sign(alternativeRemoteCommitTx, channelKeys.fundingKey(fundingTxIndex))
                     CommitSigTlv.AlternativeFeerateSig(feerate, alternativeSig)
                 }
-                CommitSig(params.channelId, sig, listOf(), TlvStream(CommitSigTlv.AlternativeFeerateSigs(alternativeSigs)))
+                add(CommitSigTlv.AlternativeFeerateSigs(alternativeSigs))
             }
-            else -> CommitSig(params.channelId, sig, htlcSigs.toList())
         }
+        val commitSig = CommitSig(params.channelId, sig, htlcSigs.toList(), TlvStream(tlvs))
         val commitment1 = copy(nextRemoteCommit = NextRemoteCommit(commitSig, RemoteCommit(remoteCommit.index + 1, spec, remoteCommitTx.tx.txid, remoteNextPerCommitmentPoint)))
         return Pair(commitment1, commitSig)
     }
@@ -951,6 +951,25 @@ data class Commitments(
          */
         val alternativeFeerates = listOf(1.sat, 2.sat, 5.sat, 10.sat).map { FeeratePerKw(FeeratePerByte(it)) }
 
+        /**
+         * Our peer may publish an alternative version of their commitment using a different feerate.
+         * This function lists all the alternative commitments they have signatures for.
+         */
+        fun alternativeFeerateCommits(commitments: Commitments, channelKeys: KeyManager.ChannelKeys): List<RemoteCommit> {
+            return buildList {
+                add(commitments.latest.remoteCommit)
+                commitments.latest.nextRemoteCommit?.let { add(it.commit) }
+            }.filter { remoteCommit ->
+                remoteCommit.spec.htlcs.isEmpty()
+            }.flatMap { remoteCommit ->
+                alternativeFeerates.map { feerate ->
+                    val alternativeSpec = remoteCommit.spec.copy(feerate = feerate)
+                    val (alternativeRemoteCommitTx, _) = makeRemoteTxs(channelKeys, remoteCommit.index, commitments.params.localParams, commitments.params.remoteParams, commitments.latest.fundingTxIndex, commitments.latest.remoteFundingPubkey, commitments.latest.commitInput, remoteCommit.remotePerCommitmentPoint, alternativeSpec)
+                    RemoteCommit(remoteCommit.index, alternativeSpec, alternativeRemoteCommitTx.tx.txid, remoteCommit.remotePerCommitmentPoint)
+                }
+            }
+        }
+
         fun makeLocalTxs(
             channelKeys: KeyManager.ChannelKeys,
             commitTxNumber: Long,
diff --git a/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt b/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt
index 483e79111..da978924e 100644
--- a/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt
+++ b/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt
@@ -507,19 +507,7 @@ sealed class ChannelStateWithCommitments : PersistedChannelState() {
                 }
                 else -> {
                     // Our peer may publish an alternative version of their commitment using a different feerate.
-                    val alternativeFeerateCommits = buildList {
-                        add(commitments.latest.remoteCommit)
-                        commitments.latest.nextRemoteCommit?.let { add(it.commit) }
-                    }.filter { remoteCommit ->
-                        remoteCommit.spec.htlcs.isEmpty()
-                    }.flatMap { remoteCommit ->
-                        Commitments.alternativeFeerates.map { feerate ->
-                            val alternativeSpec = remoteCommit.spec.copy(feerate = feerate)
-                            val (alternativeRemoteCommitTx, _) = Commitments.makeRemoteTxs(channelKeys(), remoteCommit.index, commitments.params.localParams, commitments.params.remoteParams, commitments.latest.fundingTxIndex, commitments.latest.remoteFundingPubkey, commitments.latest.commitInput, remoteCommit.remotePerCommitmentPoint, alternativeSpec)
-                            RemoteCommit(remoteCommit.index, alternativeSpec, alternativeRemoteCommitTx.tx.txid, remoteCommit.remotePerCommitmentPoint)
-                        }
-                    }
-                    when (val remoteCommit = alternativeFeerateCommits.find { it.txid == tx.txid }) {
+                    when (val remoteCommit = Commitments.alternativeFeerateCommits(commitments, channelKeys()).find { it.txid == tx.txid }) {
                         null -> {
                             logger.warning { "unrecognized tx=${tx.txid}" }
                             // This can happen if the user has two devices.