diff --git a/navalplanner-gantt-zk/pom.xml b/navalplanner-gantt-zk/pom.xml
index 55c942b60..8ffde6340 100644
--- a/navalplanner-gantt-zk/pom.xml
+++ b/navalplanner-gantt-zk/pom.xml
@@ -22,6 +22,10 @@
             <groupId>commons-logging</groupId>
             <artifactId>commons-logging</artifactId>
         </dependency>
+        <dependency>
+            <groupId>commons-lang</groupId>
+            <artifactId>commons-lang</artifactId>
+        </dependency>
         <!-- ZK  -->
         <dependency>
             <groupId>org.zkoss.zk</groupId>
diff --git a/navalplanner-gantt-zk/src/main/java/org/zkoss/ganttz/data/Dependency.java b/navalplanner-gantt-zk/src/main/java/org/zkoss/ganttz/data/Dependency.java
index 630ab4b05..f62b4398c 100644
--- a/navalplanner-gantt-zk/src/main/java/org/zkoss/ganttz/data/Dependency.java
+++ b/navalplanner-gantt-zk/src/main/java/org/zkoss/ganttz/data/Dependency.java
@@ -3,6 +3,9 @@ package org.zkoss.ganttz.data;
 import java.util.Collection;
 import java.util.Date;
 
+import org.apache.commons.lang.builder.EqualsBuilder;
+import org.apache.commons.lang.builder.HashCodeBuilder;
+
 /**
  * This class represents a dependency. Contains the source and the destination.
  * It also specifies the type of the relationship. <br/>
@@ -74,12 +77,8 @@ public class Dependency {
 
     @Override
     public int hashCode() {
-        final int prime = 31;
-        int result = 1;
-        result = prime * result
-                + ((destination == null) ? 0 : destination.hashCode());
-        result = prime * result + ((source == null) ? 0 : source.hashCode());
-        return result;
+        return new HashCodeBuilder().append(source).append(destination).append(
+                type).toHashCode();
     }
 
     @Override
@@ -91,17 +90,9 @@ public class Dependency {
         if (getClass() != obj.getClass())
             return false;
         Dependency other = (Dependency) obj;
-        if (destination == null) {
-            if (other.destination != null)
-                return false;
-        } else if (!destination.equals(other.destination))
-            return false;
-        if (source == null) {
-            if (other.source != null)
-                return false;
-        } else if (!source.equals(other.source))
-            return false;
-        return true;
+        return new EqualsBuilder().append(this.destination, other.destination)
+                .append(this.source, other.source)
+                .append(this.type, other.type).isEquals();
     }
 
     public Task getSource() {