diff --git a/core/src/test/java/hudson/UtilTest.java b/core/src/test/java/hudson/UtilTest.java
index ca7e57a681..7a5ea90c5c 100644
--- a/core/src/test/java/hudson/UtilTest.java
+++ b/core/src/test/java/hudson/UtilTest.java
@@ -30,6 +30,7 @@ import java.util.HashMap;
 import java.util.Locale;
 import java.util.Properties;
 import java.util.concurrent.Callable;
+import java.util.concurrent.atomic.AtomicReference;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;