diff --git a/ganttzk/pom.xml b/ganttzk/pom.xml
index 5221c2c5a..ffb1d8fd9 100644
--- a/ganttzk/pom.xml
+++ b/ganttzk/pom.xml
@@ -58,6 +58,11 @@
             <groupId>commons-lang</groupId>
             <artifactId>commons-lang</artifactId>
         </dependency>
+        <!-- Commons collections -->
+        <dependency>
+            <groupId>commons-collections</groupId>
+            <artifactId>commons-collections</artifactId>
+        </dependency>
         <!-- ZK  -->
         <dependency>
             <groupId>org.zkoss.zk</groupId>
diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
index aa8cd5a16..84b0c4212 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
@@ -30,6 +30,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.commons.collections.CollectionUtils;
 import org.joda.time.LocalDate;
 import org.zkoss.ganttz.adapters.DomainDependency;
 import org.zkoss.ganttz.adapters.IAdapterToTaskFundamentalProperties;
@@ -39,13 +40,13 @@ import org.zkoss.ganttz.adapters.PlannerConfiguration;
 import org.zkoss.ganttz.data.Dependency;
 import org.zkoss.ganttz.data.DependencyType;
 import org.zkoss.ganttz.data.GanttDiagramGraph;
-import org.zkoss.ganttz.data.GanttDiagramGraph.GanttZKDiagramGraph;
 import org.zkoss.ganttz.data.ITaskFundamentalProperties;
 import org.zkoss.ganttz.data.Milestone;
 import org.zkoss.ganttz.data.Position;
 import org.zkoss.ganttz.data.Task;
 import org.zkoss.ganttz.data.TaskContainer;
 import org.zkoss.ganttz.data.TaskLeaf;
+import org.zkoss.ganttz.data.GanttDiagramGraph.GanttZKDiagramGraph;
 import org.zkoss.ganttz.data.criticalpath.CriticalPathCalculator;
 import org.zkoss.ganttz.extensions.IContext;
 import org.zkoss.ganttz.timetracker.TimeTracker;
@@ -386,11 +387,16 @@ public class FunctionalityExposedForExtensions<T> implements IContext<T> {
         List<Task> criticalPath = criticalPathCalculator
                 .calculateCriticalPath(diagramGraph);
         for (Task task : diagramGraph.getTasks()) {
-            if (criticalPath.contains(task)) {
-                task.setInCriticalPath(true);
-            } else {
-                task.setInCriticalPath(false);
-            }
+            task.setInCriticalPath(isInCriticalPath(criticalPath, task));
+        }
+    }
+
+    private boolean isInCriticalPath(List<Task> criticalPath, Task task) {
+        if (task.isContainer() && !task.isExpanded()) {
+            List<Task> allTaskLeafs = ((TaskContainer) task).getAllTaskLeafs();
+            return CollectionUtils.containsAny(criticalPath, allTaskLeafs);
+        } else {
+            return criticalPath.contains(task);
         }
     }