diff --git a/server/src/main/java/org/elasticsearch/action/ActionListener.java b/server/src/main/java/org/elasticsearch/action/ActionListener.java
index a158669d936fe..5b577eebcf6b0 100644
--- a/server/src/main/java/org/elasticsearch/action/ActionListener.java
+++ b/server/src/main/java/org/elasticsearch/action/ActionListener.java
@@ -390,7 +390,9 @@ static <Response> ActionListener<Response> assertOnce(ActionListener<Response> d
 
                 private void assertFirstRun() {
                     var previousRun = firstCompletion.compareAndExchange(null, new ElasticsearchException("executed already"));
-                    assert previousRun == null : "[" + delegate + "] " + previousRun; // reports the stack traces of both completions
+                    assert previousRun == null
+                        // reports the stack traces of both completions
+                        : new AssertionError("[" + delegate + "]", previousRun);
                 }
 
                 @Override