diff --git a/runtime-rpc/src/main/java/org/capnproto/TwoPartyVatNetwork.java b/runtime-rpc/src/main/java/org/capnproto/TwoPartyVatNetwork.java
index 7929286..b8a2c12 100644
--- a/runtime-rpc/src/main/java/org/capnproto/TwoPartyVatNetwork.java
+++ b/runtime-rpc/src/main/java/org/capnproto/TwoPartyVatNetwork.java
@@ -1,6 +1,7 @@
 package org.capnproto;
 
 import java.io.IOException;
+import java.nio.channels.AsynchronousByteChannel;
 import java.nio.channels.AsynchronousSocketChannel;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
@@ -20,13 +21,13 @@ public class TwoPartyVatNetwork
 
     private CompletableFuture<java.lang.Void> previousWrite = CompletableFuture.completedFuture(null);
     private final CompletableFuture<java.lang.Void> disconnectPromise = new CompletableFuture<>();
-    private final AsynchronousSocketChannel channel;
+    private final AsynchronousByteChannel channel;
     private final RpcTwoPartyProtocol.Side side;
     private final MessageBuilder peerVatId = new MessageBuilder(4);
     private boolean accepted;
     private MessageTap tap;
 
-    public TwoPartyVatNetwork(AsynchronousSocketChannel channel, RpcTwoPartyProtocol.Side side) {
+    public TwoPartyVatNetwork(AsynchronousByteChannel channel, RpcTwoPartyProtocol.Side side) {
         this.channel = channel;
         this.side = side;
         this.peerVatId.initRoot(RpcTwoPartyProtocol.VatId.factory).setSide(
@@ -114,7 +115,9 @@ public class TwoPartyVatNetwork
 
         var result = this.previousWrite.thenRun(() -> {
             try {
-                this.channel.shutdownOutput();
+                if (this.channel instanceof AsynchronousSocketChannel) {
+                    ((AsynchronousSocketChannel)this.channel).shutdownOutput();
+                }
             }
             catch (Exception ioExc) {
             }