diff --git a/commons-ip-math/src/main/java/net/ripe/commons/ip/StartAndSizeComparator.java b/commons-ip-math/src/main/java/net/ripe/commons/ip/StartAndSizeComparator.java
index <HASH>..<HASH> 100644
--- a/commons-ip-math/src/main/java/net/ripe/commons/ip/StartAndSizeComparator.java
+++ b/commons-ip-math/src/main/java/net/ripe/commons/ip/StartAndSizeComparator.java
@@ -1,8 +1,12 @@
 package net.ripe.commons.ip;
 
+import java.io.Serializable;
+
 public class StartAndSizeComparator<C extends Rangeable<C, R>, R extends Range<C, R>>
-        implements RangeComparator<C, R> {
+        implements RangeComparator<C, R>, Serializable {
 
+    private static final long serialVersionUID = 6525126518038448733L;
+    
     private static StartAndSizeComparator<?, ?> instance;
 
     @SuppressWarnings({"unchecked"})
Serial version uid added to match speed test...