diff --git a/lib/java/build.xml b/lib/java/build.xml
index de9b018..dbbaf6b 100644
--- a/lib/java/build.xml
+++ b/lib/java/build.xml
@@ -180,6 +180,8 @@
       classpathref="test.classpath" failonerror="true" />
     <java classname="org.apache.thrift.test.JavaBeansTest"
       classpathref="test.classpath" failonerror="true" />
+    <java classname="org.apache.thrift.test.UnionTest"
+      classpathref="test.classpath" failonerror="true" />
   </target>
 
   <target name="generate">