diff --git a/RELEASE-NOTES.html b/RELEASE-NOTES.html
index 55e085988..24b4db57a 100644
--- a/RELEASE-NOTES.html
+++ b/RELEASE-NOTES.html
@@ -33,6 +33,7 @@ No interface changes, or deprecations have occurred.
 <li>ReferenceMap - Changed to extend AbstractHashedMap, thus gaining a mapIterator() and subclassability</li>
 <li>Fast3Map - Make Serializable [27946]</li>
 <li>Fast3Map - Add clone() method</li>
+<li>FixedSizeMap - Make Serializable [18815]</li>
 <li>MultiKey - Add getKey(index) and size() methods and make constructor public</li>
 <li>MultiHashMap - Add five methods to improve the API</li>
 <li>AbstractHashedMap,AbstractLinkedMap - Add methods to access entry methods when protected scope blocks</li>
diff --git a/data/test/FixedSizeMap.emptyCollection.version3.1.obj b/data/test/FixedSizeMap.emptyCollection.version3.1.obj
new file mode 100644
index 000000000..a22abc377
Binary files /dev/null and b/data/test/FixedSizeMap.emptyCollection.version3.1.obj differ
diff --git a/data/test/FixedSizeMap.fullCollection.version3.1.obj b/data/test/FixedSizeMap.fullCollection.version3.1.obj
new file mode 100644
index 000000000..2ab7b8572
Binary files /dev/null and b/data/test/FixedSizeMap.fullCollection.version3.1.obj differ
diff --git a/src/java/org/apache/commons/collections/map/FixedSizeMap.java b/src/java/org/apache/commons/collections/map/FixedSizeMap.java
index d2fde29d3..64831648a 100644
--- a/src/java/org/apache/commons/collections/map/FixedSizeMap.java
+++ b/src/java/org/apache/commons/collections/map/FixedSizeMap.java
@@ -15,6 +15,10 @@
  */
 package org.apache.commons.collections.map;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Map;
@@ -38,13 +42,17 @@ import org.apache.commons.collections.set.UnmodifiableSet;
  * is not always unsupported.
  *
  * @since Commons Collections 3.0
- * @version $Revision: 1.5 $ $Date: 2004/02/18 01:13:19 $
+ * @version $Revision: 1.6 $ $Date: 2004/04/02 21:15:05 $
  * 
  * @author Stephen Colebourne
  * @author Paul Jack
  */
 public class FixedSizeMap
-        extends AbstractMapDecorator implements Map, BoundedMap {
+        extends AbstractMapDecorator
+        implements Map, BoundedMap, Serializable {
+
+    /** Serialization version */
+    private static final long serialVersionUID = 7450927208116179316L;
 
     /**
      * Factory method to create a fixed size map.
@@ -66,7 +74,24 @@ public class FixedSizeMap
     protected FixedSizeMap(Map map) {
         super(map);
     }
-    
+
+    //-----------------------------------------------------------------------
+    /**
+     * Write the map out using a custom routine.
+     */
+    private void writeObject(ObjectOutputStream out) throws IOException {
+        out.defaultWriteObject();
+        out.writeObject(map);
+    }
+
+    /**
+     * Read the map in using a custom routine.
+     */
+    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+        in.defaultReadObject();
+        map = (Map) in.readObject();
+    }
+
     //-----------------------------------------------------------------------
     public Object put(Object key, Object value) {
         if (map.containsKey(key) == false) {
diff --git a/src/test/org/apache/commons/collections/map/TestFixedSizeMap.java b/src/test/org/apache/commons/collections/map/TestFixedSizeMap.java
index 3af2e59cb..982af6253 100644
--- a/src/test/org/apache/commons/collections/map/TestFixedSizeMap.java
+++ b/src/test/org/apache/commons/collections/map/TestFixedSizeMap.java
@@ -26,7 +26,7 @@ import junit.framework.TestSuite;
  * implementation.
  *
  * @since Commons Collections 3.0
- * @version $Revision: 1.5 $ $Date: 2004/02/18 01:20:38 $
+ * @version $Revision: 1.6 $ $Date: 2004/04/02 21:15:05 $
  * 
  * @author Stephen Colebourne
  */
@@ -63,4 +63,18 @@ public class TestFixedSizeMap extends AbstractTestMap {
         return false;
     }
 
+    public String getCompatibilityVersion() {
+        return "3.1";
+    }
+
+//    public void testCreate() throws Exception {
+//        resetEmpty();
+//        writeExternalFormToDisk(
+//            (java.io.Serializable) map,
+//            "D:/dev/collections/data/test/FixedSizeMap.emptyCollection.version3.1.obj");
+//        resetFull();
+//        writeExternalFormToDisk(
+//            (java.io.Serializable) map,
+//            "D:/dev/collections/data/test/FixedSizeMap.fullCollection.version3.1.obj");
+//    }
 }