diff --git a/core/src/main/java/io/undertow/client/http2/Http2ClientConnection.java b/core/src/main/java/io/undertow/client/http2/Http2ClientConnection.java
index <HASH>..<HASH> 100644
--- a/core/src/main/java/io/undertow/client/http2/Http2ClientConnection.java
+++ b/core/src/main/java/io/undertow/client/http2/Http2ClientConnection.java
@@ -127,7 +127,7 @@ public class Http2ClientConnection implements ClientConnection {
     }
 
     @Override
-    public void sendRequest(ClientRequest request, ClientCallback<ClientExchange> clientCallback) {
+    public synchronized void sendRequest(ClientRequest request, ClientCallback<ClientExchange> clientCallback) {
         request.getRequestHeaders().put(METHOD, request.getMethod().toString());
         boolean connectRequest = request.getMethod().equals(Methods.CONNECT);
         if(!connectRequest) {
UNDERTOW-<I> Http2ClientConnection.sendRequest should be syncronized to make sure streams arrive in order