diff --git a/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker.java b/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker.java
index 58a0d46a6d..127a1eeda0 100644
--- a/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker.java
+++ b/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker.java
@@ -40,11 +40,11 @@ public abstract class WebSocketClientHandshaker {
 
     private final WebSocketVersion version;
 
-    private boolean handshakeComplete;
+    private volatile boolean handshakeComplete;
 
     private final String expectedSubprotocol;
 
-    private String actualSubprotocol;
+    private volatile String actualSubprotocol;
 
     protected final HttpHeaders customHeaders;