diff --git a/src/java/org/apache/commons/math/util/DefaultTransformer.java b/src/java/org/apache/commons/math/util/DefaultTransformer.java
index 0521db5a5..8618e3743 100644
--- a/src/java/org/apache/commons/math/util/DefaultTransformer.java
+++ b/src/java/org/apache/commons/math/util/DefaultTransformer.java
@@ -30,7 +30,9 @@ import org.apache.commons.math.MathException;
  * @version $Revision$ $Date$
  */
 public class DefaultTransformer implements NumberTransformer, Serializable {
-    
+    // TODO: Add Serializable documentation
+    // TODO: Check Serializable implementation
+   
     /** Serializable version identifier */
     private static final long serialVersionUID = 4019938025047800455L;
     
diff --git a/src/java/org/apache/commons/math/util/NumberTransformer.java b/src/java/org/apache/commons/math/util/NumberTransformer.java
index a284ed7f6..9f34ece7e 100644
--- a/src/java/org/apache/commons/math/util/NumberTransformer.java
+++ b/src/java/org/apache/commons/math/util/NumberTransformer.java
@@ -16,15 +16,16 @@
  */
 package org.apache.commons.math.util;
 
-import java.io.Serializable;
-
 import org.apache.commons.math.MathException;
 
 /**
  * Subclasses implementing this interface can transform Objects to doubles.
  * @version $Revision$ $Date$
+ * 
+ * No longer extends Serializable since 2.0
+ * 
  */
-public interface NumberTransformer extends Serializable {
+public interface NumberTransformer {
     
     /**
      * Implementing this interface provides a facility to transform
diff --git a/src/java/org/apache/commons/math/util/TransformerMap.java b/src/java/org/apache/commons/math/util/TransformerMap.java
index 6b67bdef9..04fbf5897 100644
--- a/src/java/org/apache/commons/math/util/TransformerMap.java
+++ b/src/java/org/apache/commons/math/util/TransformerMap.java
@@ -32,6 +32,8 @@ import org.apache.commons.math.MathException;
  * @version $Revision$ $Date$
  */
 public class TransformerMap implements NumberTransformer, Serializable {
+    // TODO: Add Serializable documentation
+    // TODO: Check Serializable implementation
 
     /** Serializable version identifier */
     private static final long serialVersionUID = 4605318041528645258L;
diff --git a/src/test/org/apache/commons/math/stat/descriptive/MixedListUnivariateImplTest.java b/src/test/org/apache/commons/math/stat/descriptive/MixedListUnivariateImplTest.java
index 88ea10901..b9afcabbf 100644
--- a/src/test/org/apache/commons/math/stat/descriptive/MixedListUnivariateImplTest.java
+++ b/src/test/org/apache/commons/math/stat/descriptive/MixedListUnivariateImplTest.java
@@ -16,6 +16,7 @@
  */
 package org.apache.commons.math.stat.descriptive;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -184,7 +185,7 @@ public final class MixedListUnivariateImplTest extends TestCase {
         }
     }
 
-    public static final class FooTransformer implements NumberTransformer {
+    public static final class FooTransformer implements NumberTransformer, Serializable {
         private static final long serialVersionUID = -4252248129291326127L;
         public double transform(Object o) {
             return Double.parseDouble(((Foo) o).heresFoo());
@@ -197,7 +198,7 @@ public final class MixedListUnivariateImplTest extends TestCase {
         }
     }
 
-    public static final class BarTransformer implements NumberTransformer {
+    public static final class BarTransformer implements NumberTransformer, Serializable {
         private static final long serialVersionUID = -1768345377764262043L;
         public double transform(Object o) {
             return Double.parseDouble(((Bar) o).heresBar());