diff --git a/d2/src/main/java/com/linkedin/d2/balancer/util/WarmUpLoadBalancer.java b/d2/src/main/java/com/linkedin/d2/balancer/util/WarmUpLoadBalancer.java
index eafad048e1..4ea82df76d 100644
--- a/d2/src/main/java/com/linkedin/d2/balancer/util/WarmUpLoadBalancer.java
+++ b/d2/src/main/java/com/linkedin/d2/balancer/util/WarmUpLoadBalancer.java
@@ -153,7 +153,8 @@ public void onSuccess(None result) {
 
   private void prepareWarmUp(Callback<None> callback)
   {
-    AtomicBoolean hasTimedOut = new AtomicBoolean(false);
+    // not to be thread-safe, but just to be effectively final to be used in lambdas
+    final AtomicBoolean hasTimedOut = new AtomicBoolean(false);
 
     try {
       _downstreamServicesFetcher.getServiceNames(serviceNames -> {