diff --git a/jetty-core/jetty-slf4j-impl/src/main/java/org/eclipse/jetty/logging/StdErrAppender.java b/jetty-core/jetty-slf4j-impl/src/main/java/org/eclipse/jetty/logging/StdErrAppender.java
index 5d3aae6682ac..719f2e7afd78 100644
--- a/jetty-core/jetty-slf4j-impl/src/main/java/org/eclipse/jetty/logging/StdErrAppender.java
+++ b/jetty-core/jetty-slf4j-impl/src/main/java/org/eclipse/jetty/logging/StdErrAppender.java
@@ -207,7 +207,9 @@ private void appendCause(StringBuilder builder, Throwable cause, String indent,
         builder.append(EOL).append(indent);
         if (visited.contains(cause))
         {
-            builder.append("[CIRCULAR REFERENCE: ").append(cause).append("]");
+            builder.append("[CIRCULAR REFERENCE: ");
+            appendEscaped(builder, cause.toString());
+            builder.append("]");
             return;
         }
         visited.add(cause);