diff --git a/avaje-jex/src/test/java/io/avaje/jex/jdk/AutoCloseIterator.java b/avaje-jex/src/test/java/io/avaje/jex/jdk/AutoCloseIterator.java
index 36ce498..01528d6 100644
--- a/avaje-jex/src/test/java/io/avaje/jex/jdk/AutoCloseIterator.java
+++ b/avaje-jex/src/test/java/io/avaje/jex/jdk/AutoCloseIterator.java
@@ -5,7 +5,7 @@
 public class AutoCloseIterator<E> implements Iterator<E>, AutoCloseable {
 
   private final Iterator<E> it;
-  private boolean closed;
+  private volatile boolean closed;
 
   public AutoCloseIterator(Iterator<E> it) {
     this.it = it;