diff --git a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/message/MessageOutputStream.java b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/message/MessageOutputStream.java
index b5982b28d2d..bc9ab1bab05 100644
--- a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/message/MessageOutputStream.java
+++ b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/message/MessageOutputStream.java
@@ -153,6 +153,9 @@ public class MessageOutputStream extends OutputStream
             // Any flush after the first will be a CONTINUATION frame.
             frame.setIsContinuation();
 
+            // Buffer has been sent, buffer should have been consumed
+            assert buffer.remaining() == 0;
+
             BufferUtil.flipToFill(buffer);
         }
     }
diff --git a/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/message/MessageOutputStreamTest.java b/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/message/MessageOutputStreamTest.java
index 43dfe4145b6..ae9d6515431 100644
--- a/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/message/MessageOutputStreamTest.java
+++ b/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/message/MessageOutputStreamTest.java
@@ -18,11 +18,6 @@
 
 package org.eclipse.jetty.websocket.common.message;
 
-import static org.hamcrest.Matchers.allOf;
-import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.is;
-
-import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.Arrays;
 
@@ -33,7 +28,6 @@ import org.eclipse.jetty.websocket.api.WebSocketPolicy;
 import org.eclipse.jetty.websocket.api.extensions.OutgoingFrames;
 import org.eclipse.jetty.websocket.common.WebSocketSession;
 import org.eclipse.jetty.websocket.common.io.FramePipes;
-import org.eclipse.jetty.websocket.common.io.LocalWebSocketConnection;
 import org.eclipse.jetty.websocket.common.io.LocalWebSocketSession;
 import org.eclipse.jetty.websocket.common.scopes.SimpleContainerScope;
 import org.eclipse.jetty.websocket.common.scopes.WebSocketContainerScope;
@@ -45,6 +39,10 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TestName;
 
+import static org.hamcrest.Matchers.allOf;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.is;
+
 public class MessageOutputStreamTest
 {
     private static final Logger LOG = Log.getLogger(MessageOutputStreamTest.class);
@@ -83,6 +81,7 @@ public class MessageOutputStreamTest
         remoteSocket = new TrackingSocket("remote");
         WebSocketSession remoteSession = new LocalWebSocketSession(containerScope,testname,remoteSocket);
         OutgoingFrames socketPipe = FramePipes.to(remoteSession);
+        remoteSession.open();
 
         // Local Session
         TrackingSocket localSocket = new TrackingSocket("local");
diff --git a/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/test/OutgoingFramesCapture.java b/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/test/OutgoingFramesCapture.java
index ba406f89da7..03d14906ad3 100644
--- a/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/test/OutgoingFramesCapture.java
+++ b/jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/test/OutgoingFramesCapture.java
@@ -18,9 +18,7 @@
 
 package org.eclipse.jetty.websocket.common.test;
 
-import static org.hamcrest.Matchers.greaterThanOrEqualTo;
-import static org.hamcrest.Matchers.is;
-
+import java.nio.ByteBuffer;
 import java.util.LinkedList;
 
 import org.eclipse.jetty.util.BufferUtil;
@@ -32,6 +30,9 @@ import org.eclipse.jetty.websocket.common.OpCode;
 import org.eclipse.jetty.websocket.common.WebSocketFrame;
 import org.junit.Assert;
 
+import static org.hamcrest.Matchers.greaterThanOrEqualTo;
+import static org.hamcrest.Matchers.is;
+
 public class OutgoingFramesCapture implements OutgoingFrames
 {
     private LinkedList<WebSocketFrame> frames = new LinkedList<>();
@@ -89,6 +90,10 @@ public class OutgoingFramesCapture implements OutgoingFrames
     public void outgoingFrame(Frame frame, WriteCallback callback, BatchMode batchMode)
     {
         frames.add(WebSocketFrame.copy(frame));
+        // Consume bytes
+        ByteBuffer payload = frame.getPayload();
+        payload.position(payload.limit());
+        // notify callback
         if (callback != null)
         {
             callback.writeSuccess();