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 d675466..bdc0e78 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
@@ -54,7 +54,7 @@
 
     public void addBuffer(byte buf[], int offset, int length)
     {
-        if (buf.length + length > maxSize)
+        if (this.length + length > maxSize)
         {
             throw new MessageTooLargeException("Frame is too large");
         }