diff --git a/docs/release-notes/eclair-vnext.md b/docs/release-notes/eclair-vnext.md
index c2e4f7f292..0a29a98d33 100644
--- a/docs/release-notes/eclair-vnext.md
+++ b/docs/release-notes/eclair-vnext.md
@@ -82,7 +82,7 @@ This release contains many other API updates:
 - `findroute`, `findroutetonode` and `findroutebetweennodes` now accept `--ignoreShortChannelIds` to specify channels you want to be ignored in path-finding (#1969)
 - `findroute`, `findroutetonode` and `findroutebetweennodes` now accept `--maxFeeMsat` to specify an upper bound of fees (#1969)
 - `getsentinfo` output includes `failedNode` field for all failed routes
-- for `payinvoice` and `sendtonode`, `--feeThresholdSat` has been renamed to `--maxFeeFlat`
+- for `payinvoice` and `sendtonode`, `--feeThresholdSat` has been renamed to `--maxFeeFlatSat`
 
 Have a look at our [API documentation](https://acinq.github.io/eclair) for more details.
 
diff --git a/eclair-node/src/main/scala/fr/acinq/eclair/api/handlers/Payment.scala b/eclair-node/src/main/scala/fr/acinq/eclair/api/handlers/Payment.scala
index df39748fca..67f341ec71 100644
--- a/eclair-node/src/main/scala/fr/acinq/eclair/api/handlers/Payment.scala
+++ b/eclair-node/src/main/scala/fr/acinq/eclair/api/handlers/Payment.scala
@@ -38,7 +38,7 @@ trait Payment {
   }
 
   val payInvoice: Route = postRequest("payinvoice") { implicit t =>
-    formFields(invoiceFormParam, amountMsatFormParam.?, "maxAttempts".as[Int].?, "maxFeeFlat".as[Satoshi].?, "maxFeePct".as[Double].?, "externalId".?, "blocking".as[Boolean].?, "pathFindingExperimentName".?) {
+    formFields(invoiceFormParam, amountMsatFormParam.?, "maxAttempts".as[Int].?, "maxFeeFlatSat".as[Satoshi].?, "maxFeePct".as[Double].?, "externalId".?, "blocking".as[Boolean].?, "pathFindingExperimentName".?) {
       case (invoice@PaymentRequest(_, Some(amount), _, nodeId, _, _), None, maxAttempts, maxFeeFlat_opt, maxFeePct_opt, externalId_opt, blocking_opt, pathFindingExperimentName_opt) =>
         blocking_opt match {
           case Some(true) => complete(eclairApi.sendBlocking(externalId_opt, amount, invoice, maxAttempts, maxFeeFlat_opt, maxFeePct_opt, pathFindingExperimentName_opt))
@@ -72,7 +72,7 @@ trait Payment {
   }
 
   val sendToNode: Route = postRequest("sendtonode") { implicit t =>
-    formFields(amountMsatFormParam, nodeIdFormParam, "maxAttempts".as[Int].?, "maxFeeFlat".as[Satoshi].?, "maxFeePct".as[Double].?, "externalId".?, "pathFindingExperimentName".?) {
+    formFields(amountMsatFormParam, nodeIdFormParam, "maxAttempts".as[Int].?, "maxFeeFlatSat".as[Satoshi].?, "maxFeePct".as[Double].?, "externalId".?, "pathFindingExperimentName".?) {
       case (amountMsat, nodeId, maxAttempts_opt, maxFeeFlat_opt, maxFeePct_opt, externalId_opt, pathFindingExperimentName_opt) =>
         complete(eclairApi.sendWithPreimage(externalId_opt, nodeId, amountMsat, randomBytes32(), maxAttempts_opt, maxFeeFlat_opt, maxFeePct_opt, pathFindingExperimentName_opt))
     }
diff --git a/eclair-node/src/test/scala/fr/acinq/eclair/api/ApiServiceSpec.scala b/eclair-node/src/test/scala/fr/acinq/eclair/api/ApiServiceSpec.scala
index 4e80f7fe99..23b8d8c4c1 100644
--- a/eclair-node/src/test/scala/fr/acinq/eclair/api/ApiServiceSpec.scala
+++ b/eclair-node/src/test/scala/fr/acinq/eclair/api/ApiServiceSpec.scala
@@ -661,7 +661,7 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
     eclair.send(any, any, any, any, any, any, any)(any[Timeout]) returns Future.successful(UUID.randomUUID())
     val mockService = new MockService(eclair)
 
-    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "123", "maxFeeFlat" -> "112233", "maxFeePct" -> "2.34", "externalId" -> "42").toEntity) ~>
+    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "123", "maxFeeFlatSat" -> "112233", "maxFeePct" -> "2.34", "externalId" -> "42").toEntity) ~>
       addCredentials(BasicHttpCredentials("", mockApi().password)) ~>
       Route.seal(mockService.payInvoice) ~>
       check {
@@ -678,7 +678,7 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
     eclair.send(any, any, any, any, any, any, any)(any[Timeout]) returns Future.successful(UUID.randomUUID())
     val mockService = new MockService(eclair)
 
-    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "456", "maxFeeFlat" -> "10", "maxFeePct" -> "0.5").toEntity) ~>
+    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "456", "maxFeeFlatSat" -> "10", "maxFeePct" -> "0.5").toEntity) ~>
       addCredentials(BasicHttpCredentials("", mockApi().password)) ~>
       Route.seal(mockService.route) ~>
       check {
@@ -695,7 +695,7 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
     eclair.send(any, any, any, any, any, any, any)(any[Timeout]) returns Future.successful(UUID.randomUUID())
     val mockService = new MockService(eclair)
 
-    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "456", "maxFeeFlat" -> "10", "maxFeePct" -> "0.5", "pathFindingExperimentName" -> "my-test-experiment").toEntity) ~>
+    Post("/payinvoice", FormData("invoice" -> invoice, "amountMsat" -> "456", "maxFeeFlatSat" -> "10", "maxFeePct" -> "0.5", "pathFindingExperimentName" -> "my-test-experiment").toEntity) ~>
       addCredentials(BasicHttpCredentials("", mockApi().password)) ~>
       Route.seal(mockService.route) ~>
       check {
@@ -753,7 +753,7 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
     val mockService = new MockService(eclair)
     val remoteNodeId = PublicKey(hex"030bb6a5e0c6b203c7e2180fb78c7ba4bdce46126761d8201b91ddac089cdecc87")
 
-    Post("/sendtonode", FormData("amountMsat" -> "123", "nodeId" -> "030bb6a5e0c6b203c7e2180fb78c7ba4bdce46126761d8201b91ddac089cdecc87", "maxFeeFlat" -> "10000", "maxFeePct" -> "2.5", "externalId" -> "42").toEntity) ~>
+    Post("/sendtonode", FormData("amountMsat" -> "123", "nodeId" -> "030bb6a5e0c6b203c7e2180fb78c7ba4bdce46126761d8201b91ddac089cdecc87", "maxFeeFlatSat" -> "10000", "maxFeePct" -> "2.5", "externalId" -> "42").toEntity) ~>
       addCredentials(BasicHttpCredentials("", mockApi().password)) ~>
       Route.seal(mockService.sendToNode) ~>
       check {