diff --git a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java
index 77dc5606a91..30efd2c592c 100644
--- a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java
+++ b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/ByteAccumulator.java
@@ -72,6 +72,9 @@ public class ByteAccumulator implements AutoCloseable
 
     public void transferTo(ByteBuffer buffer)
     {
+        // For some reason this method expects the buffer in fill mode but returns a buffer in flush mode.
+        BufferUtil.flipToFlush(buffer, 0);
+
         int availableSpace = BufferUtil.space(buffer);
         if (availableSpace < length)
         {
diff --git a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/CompressExtension.java b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/CompressExtension.java
index 957d4e6477a..426d3b00eed 100644
--- a/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/CompressExtension.java
+++ b/jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/extensions/compress/CompressExtension.java
@@ -162,6 +162,7 @@ public abstract class CompressExtension extends AbstractExtension
         ByteBuffer buffer = getBufferPool().acquire(accumulator.getLength(), false);
         try
         {
+            BufferUtil.clearToFill(buffer);
             accumulator.transferTo(buffer);
             newFrame.setPayload(buffer);
             nextIncomingFrame(newFrame);