diff --git a/htlcswitch/interfaces.go b/htlcswitch/interfaces.go
index 51a5146e..8086624a 100644
--- a/htlcswitch/interfaces.go
+++ b/htlcswitch/interfaces.go
@@ -111,8 +111,11 @@ type ChannelLink interface {
 // Peer is an interface which represents the remote lightning node inside our
 // system.
 type Peer interface {
-	// SendMessage sends message to remote peer.
-	SendMessage(lnwire.Message) error
+	// SendMessage sends message to remote peer. The second arguments
+	// denote if the method should block until the message has been sent to
+	// the remote peer. If set, this allows the caller to more strongly
+	// synchronize.
+	SendMessage(msg lnwire.Message, sync bool) error
 
 	// WipeChannel removes the channel uniquely identified by its channel
 	// point from all indexes associated with the peer.
diff --git a/htlcswitch/link_test.go b/htlcswitch/link_test.go
index 84f20953..95f11d0f 100644
--- a/htlcswitch/link_test.go
+++ b/htlcswitch/link_test.go
@@ -1392,7 +1392,7 @@ type mockPeer struct {
 	quit     chan struct{}
 }
 
-func (m *mockPeer) SendMessage(msg lnwire.Message) error {
+func (m *mockPeer) SendMessage(msg lnwire.Message, sync bool) error {
 	select {
 	case m.sentMsgs <- msg:
 	case <-m.quit:
diff --git a/htlcswitch/mock.go b/htlcswitch/mock.go
index 658b636e..42c1843c 100644
--- a/htlcswitch/mock.go
+++ b/htlcswitch/mock.go
@@ -447,7 +447,7 @@ func (s *mockServer) intersect(f messageInterceptor) {
 	s.interceptorFuncs = append(s.interceptorFuncs, f)
 }
 
-func (s *mockServer) SendMessage(message lnwire.Message) error {
+func (s *mockServer) SendMessage(message lnwire.Message, sync bool) error {
 
 	select {
 	case s.messages <- message: