diff --git a/src/main/java/net/onrc/onos/core/util/IPv4Net.java b/src/main/java/net/onrc/onos/core/util/IPv4Net.java
index 3aa5a8b..6a04635 100644
--- a/src/main/java/net/onrc/onos/core/util/IPv4Net.java
+++ b/src/main/java/net/onrc/onos/core/util/IPv4Net.java
@@ -8,17 +8,19 @@
 
 /**
  * The class representing an IPv4 network address.
+ * This class is immutable.
  */
 @JsonDeserialize(using = IPv4NetDeserializer.class)
 @JsonSerialize(using = IPv4NetSerializer.class)
-public class IPv4Net {
-    private IPv4 address;        // The IPv4 address
-    private short prefixLen;        // The prefix length
+public final class IPv4Net {
+    private final IPv4 address;         // The IPv4 address
+    private final short prefixLen;      // The prefix length
 
     /**
      * Default constructor.
      */
     public IPv4Net() {
+        this.address = null;
         this.prefixLen = 0;
     }
 
@@ -30,6 +32,8 @@
     public IPv4Net(IPv4Net other) {
         if (other.address != null)
             this.address = new IPv4(other.address);
+        else
+            this.address = null;
         this.prefixLen = other.prefixLen;
     }
 
@@ -69,15 +73,6 @@
     }
 
     /**
-     * Set the address value of the IPv4Net address.
-     *
-     * @param address the address to use.
-     */
-    public void setAddress(IPv4 address) {
-        this.address = address;
-    }
-
-    /**
      * Get the prefix length value of the IPv4Net address.
      *
      * @return the prefix length value of the IPv4Net address.
@@ -87,26 +82,6 @@
     }
 
     /**
-     * Set the prefix length value of the IPv4Net address.
-     *
-     * @param prefixLen the prefix length to use.
-     */
-    public void setPrefixLen(short prefixLen) {
-        this.prefixLen = prefixLen;
-    }
-
-    /**
-     * Set the value of the IPv4Net address.
-     *
-     * @param address   the address to use.
-     * @param prefixLen the prefix length to use.
-     */
-    public void setValue(IPv4 address, short prefixLen) {
-        this.address = address;
-        this.prefixLen = prefixLen;
-    }
-
-    /**
      * Convert the IPv4Net value to an "address/prefixLen" string.
      *
      * @return the IPv4Net value as an "address/prefixLen" string.