diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java b/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
index 263b8561f..3f17a088d 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/TaskList.java
@@ -87,7 +87,7 @@ public class TaskList extends XulElement implements AfterCompose {
             FilterAndParentExpandedPredicates predicate) {
         this.context = context;
         this.doubleClickCommand = doubleClickCommand;
-        this.currentTotalTasks = tasks;
+        this.currentTotalTasks = new ArrayList<Task>(tasks);
         this.commandsOnTasksContextualized = commandsOnTasksContextualized;
         this.disabilityConfiguration = disabilityConfiguration;
         this.predicate = predicate;