diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/TaskComponent.java b/ganttzk/src/main/java/org/zkoss/ganttz/TaskComponent.java
index ea299a028..c6cc9e8e6 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/TaskComponent.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/TaskComponent.java
@@ -218,6 +218,9 @@ public class TaskComponent extends Div implements AfterCompose {
                     : "";
         } else {
             cssClass += task.isInCriticalPath() ? " critical" : "";
+            if (!task.canBeExplicitlyMoved()) {
+                cssClass += " fixed";
+            }
         }
         cssClass += " " + task.getAssignedStatus();
         if (task.isLimiting()) {
diff --git a/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css b/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
index a9aa526b4..b27383b2f 100644
--- a/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
+++ b/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
@@ -155,6 +155,12 @@
     z-index : 99 !important;
 }
 
+/* Fixed box */
+.fixed {
+    box-shadow: 3px 3px 3px #999;
+    border: #999;
+}
+
 /* Task lane properties */
 .row {
     height: 12px;