diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
index 7d3bfb000..d5107f424 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/Task.java
@@ -149,7 +149,7 @@ public abstract class Task implements ITaskFundamentalProperties {
     }
 
     public void registerDependenciesEnforcerHook(
-            IDependenciesEnforcerHookFactory factory) {
+            IDependenciesEnforcerHookFactory<Task> factory) {
         Validate.notNull(factory);
         dependenciesEnforcerHook = factory.create(this, notifyDates);
         Validate.notNull(dependenciesEnforcerHook);