diff --git a/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/PermessageDeflateBufferTest.java b/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/PermessageDeflateBufferTest.java
new file mode 100644
index 000000000000..ef3d30fc41eb
--- /dev/null
+++ b/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/PermessageDeflateBufferTest.java
@@ -0,0 +1,133 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.websocket.tests;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.WebSocket;
+import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
+import org.eclipse.jetty.websocket.client.WebSocketClient;
+import org.eclipse.jetty.websocket.server.config.JettyWebSocketServletContainerInitializer;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class PermessageDeflateBufferTest
+{
+    private Server server;
+    private ServerConnector connector;
+    private WebSocketClient client;
+
+    // @checkstyle-disable-check : AvoidEscapedUnicodeCharactersCheck
+    private static final List<String> DICT = Arrays.asList(
+        "\uD83C\uDF09",
+        "\uD83C\uDF0A",
+        "\uD83C\uDF0B",
+        "\uD83C\uDF0C",
+        "\uD83C\uDF0D",
+        "\uD83C\uDF0F",
+        "\uD83C\uDFC0",
+        "\uD83C\uDFC1",
+        "\uD83C\uDFC2",
+        "\uD83C\uDFC3",
+        "\uD83C\uDFC4",
+        "\uD83C\uDFC5"
+    );
+
+    private static String randomText()
+    {
+        Random rnd = new Random();
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < 15000; i++)
+        {
+            sb.append(DICT.get(rnd.nextInt(DICT.size())));
+        }
+        return sb.toString();
+    }
+
+    @BeforeEach
+    public void before() throws Exception
+    {
+        server = new Server();
+        connector = new ServerConnector(server);
+        server.addConnector(connector);
+
+        ServletContextHandler contextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
+        contextHandler.setContextPath("/");
+        server.setHandler(contextHandler);
+        JettyWebSocketServletContainerInitializer.configure(contextHandler, (context, container) ->
+        {
+            container.setMaxTextMessageSize(65535);
+            container.setInputBufferSize(16384);
+            container.addMapping("/", ServerSocket.class);
+        });
+
+        server.start();
+        client = new WebSocketClient();
+        client.start();
+    }
+
+    @AfterEach
+    public void after() throws Exception
+    {
+        client.stop();
+        server.stop();
+    }
+
+    @WebSocket
+    public static class ServerSocket extends EchoSocket
+    {
+        @Override
+        public void onError(Throwable cause)
+        {
+            cause.printStackTrace();
+            super.onError(cause);
+        }
+    }
+
+    @Test
+    public void testPermessageDeflateAggregation() throws Exception
+    {
+        EventSocket socket = new EventSocket();
+        ClientUpgradeRequest clientUpgradeRequest = new ClientUpgradeRequest();
+        clientUpgradeRequest.addExtensions("permessage-deflate");
+
+        URI uri = URI.create("ws://localhost:" + connector.getLocalPort());
+        Session session = client.connect(socket, uri, clientUpgradeRequest).get(5, TimeUnit.SECONDS);
+
+        String s = randomText();
+        session.getRemote().sendString(s);
+        assertThat(socket.textMessages.poll(5, TimeUnit.SECONDS), is(s));
+
+        session.close();
+        assertTrue(socket.closeLatch.await(5, TimeUnit.SECONDS));
+    }
+}