diff --git a/ganttzk/pom.xml b/ganttzk/pom.xml
index f0545e615..0193b211d 100644
--- a/ganttzk/pom.xml
+++ b/ganttzk/pom.xml
@@ -39,6 +39,10 @@
             <groupId>org.zkoss.zk</groupId>
             <artifactId>zk</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.zkoss.zk</groupId>
+            <artifactId>zkex</artifactId>
+        </dependency>
         <!-- JGraphT  -->
         <dependency>
             <groupId>org.jgrapht</groupId>