diff --git a/source/java/org/alfresco/repo/version/common/VersionHistoryImpl.java b/source/java/org/alfresco/repo/version/common/VersionHistoryImpl.java
index 1105143a8d..4c7ad2c0f6 100644
--- a/source/java/org/alfresco/repo/version/common/VersionHistoryImpl.java
+++ b/source/java/org/alfresco/repo/version/common/VersionHistoryImpl.java
@@ -24,6 +24,7 @@
  */
 package org.alfresco.repo.version.common;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Comparator;
@@ -219,7 +220,7 @@ public class VersionHistoryImpl implements VersionHistory
      * 
      * Note: Descending create date order 
      */
-    public class VersionComparator implements Comparator<Date>
+    public class VersionComparator implements Comparator<Date>, Serializable
     {
         public int compare(Date o1, Date o2)
         {