diff --git a/src/java/org/apache/commons/lang/mutable/MutableBoolean.java b/src/java/org/apache/commons/lang/mutable/MutableBoolean.java
index a1c5103d2..fdf396a6d 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableBoolean.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableBoolean.java
@@ -27,7 +27,7 @@ import java.io.Serializable;
  * @author Apache Software Foundation
  * @version $Id$
  */
-public class MutableBoolean implements Mutable, Serializable, Comparable<MutableBoolean> {
+public class MutableBoolean implements Mutable<Boolean>, Serializable, Comparable<MutableBoolean> {
 
     /**
      * Required for serialization support.
@@ -88,8 +88,6 @@ public class MutableBoolean implements Mutable, Serializable, Comparable<Mutable
      * @return zero if this object represents the same boolean value as the argument; a positive value if this object
      *         represents true and the argument represents false; and a negative value if this object represents false
      *         and the argument represents true
-     * @throws ClassCastException
-     *             if the argument is not a MutableInt
      */
     public int compareTo(MutableBoolean other) {
         boolean anotherVal = other.value;
@@ -120,7 +118,7 @@ public class MutableBoolean implements Mutable, Serializable, Comparable<Mutable
      * 
      * @return the value as a Boolean
      */
-    public Object getValue() {
+    public Boolean getValue() {
         return Boolean.valueOf(this.value);
     }
 
@@ -152,11 +150,9 @@ public class MutableBoolean implements Mutable, Serializable, Comparable<Mutable
      *            the value to set
      * @throws NullPointerException
      *             if the object is null
-     * @throws ClassCastException
-     *             if the type is not a {@link Boolean}
      */
-    public void setValue(Object value) {
-        setValue(((Boolean) value).booleanValue());
+    public void setValue(Boolean value) {
+        this.value = value.booleanValue();
     }
 
     /**
diff --git a/src/java/org/apache/commons/lang/mutable/MutableByte.java b/src/java/org/apache/commons/lang/mutable/MutableByte.java
index b7c325654..72ead1d8d 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableByte.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableByte.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableByte extends Number implements Comparable<MutableByte>, Mutable {
+public class MutableByte extends Number implements Comparable<MutableByte>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableByte extends Number implements Comparable<MutableByte>, Muta
      * 
      * @return the value as a Byte
      */
-    public Object getValue() {
+    public Byte getValue() {
         return Byte.valueOf(this.value);
     }
 
@@ -93,11 +93,9 @@ public class MutableByte extends Number implements Comparable<MutableByte>, Muta
      *            the value to set
      * @throws NullPointerException
      *             if the object is null
-     * @throws ClassCastException
-     *             if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).byteValue());
+    public void setValue(Number value) {
+        this.value = value.byteValue();
     }
 
     //-----------------------------------------------------------------------
diff --git a/src/java/org/apache/commons/lang/mutable/MutableDouble.java b/src/java/org/apache/commons/lang/mutable/MutableDouble.java
index 2b0f7d87f..cabd5610a 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableDouble.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableDouble.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableDouble extends Number implements Comparable<MutableDouble>, Mutable {
+public class MutableDouble extends Number implements Comparable<MutableDouble>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableDouble extends Number implements Comparable<MutableDouble>,
      * 
      * @return the value as a Double
      */
-    public Object getValue() {
+    public Double getValue() {
         return new Double(this.value);
     }
 
@@ -93,11 +93,9 @@ public class MutableDouble extends Number implements Comparable<MutableDouble>,
      *            the value to set
      * @throws NullPointerException
      *             if the object is null
-     * @throws ClassCastException
-     *             if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).doubleValue());
+    public void setValue(Number value) {
+        this.value = value.doubleValue();
     }
 
     //-----------------------------------------------------------------------
@@ -296,7 +294,6 @@ public class MutableDouble extends Number implements Comparable<MutableDouble>,
      * @param other
      *            the mutable to compare to
      * @return negative if this is less, zero if equal, positive if greater
-     * @throws ClassCastException if the argument is not a MutableDouble
      */
     public int compareTo(MutableDouble other) {
         double anotherVal = other.value;
diff --git a/src/java/org/apache/commons/lang/mutable/MutableFloat.java b/src/java/org/apache/commons/lang/mutable/MutableFloat.java
index 50419a2cd..04e03fbe0 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableFloat.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableFloat.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableFloat extends Number implements Comparable<MutableFloat>, Mutable {
+public class MutableFloat extends Number implements Comparable<MutableFloat>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableFloat extends Number implements Comparable<MutableFloat>, Mu
      * 
      * @return the value as a Float
      */
-    public Object getValue() {
+    public Float getValue() {
         return new Float(this.value);
     }
 
@@ -93,11 +93,9 @@ public class MutableFloat extends Number implements Comparable<MutableFloat>, Mu
      *            the value to set
      * @throws NullPointerException
      *             if the object is null
-     * @throws ClassCastException
-     *             if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).floatValue());
+    public void setValue(Number value) {
+        this.value = value.floatValue();
     }
 
     //-----------------------------------------------------------------------
diff --git a/src/java/org/apache/commons/lang/mutable/MutableInt.java b/src/java/org/apache/commons/lang/mutable/MutableInt.java
index 20600e61e..668b717e5 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableInt.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableInt.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableInt extends Number implements Comparable<MutableInt>, Mutable {
+public class MutableInt extends Number implements Comparable<MutableInt>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableInt extends Number implements Comparable<MutableInt>, Mutabl
      * 
      * @return the value as a Integer
      */
-    public Object getValue() {
+    public Integer getValue() {
         return new Integer(this.value);
     }
 
@@ -96,8 +96,8 @@ public class MutableInt extends Number implements Comparable<MutableInt>, Mutabl
      * @throws ClassCastException
      *                  if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).intValue());
+    public void setValue(Number value) {
+        this.value = value.intValue();
     }
 
     //-----------------------------------------------------------------------
@@ -258,7 +258,6 @@ public class MutableInt extends Number implements Comparable<MutableInt>, Mutabl
      * @param other
      *                  the mutable to compare to
      * @return negative if this is less, zero if equal, positive if greater
-     * @throws ClassCastException if the argument is not a MutableInt
      */
     public int compareTo(MutableInt other) {
         int anotherVal = other.value;
diff --git a/src/java/org/apache/commons/lang/mutable/MutableLong.java b/src/java/org/apache/commons/lang/mutable/MutableLong.java
index 9e4717486..f2282fab2 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableLong.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableLong.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableLong extends Number implements Comparable<MutableLong>, Mutable {
+public class MutableLong extends Number implements Comparable<MutableLong>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableLong extends Number implements Comparable<MutableLong>, Muta
      * 
      * @return the value as a Long
      */
-    public Object getValue() {
+    public Long getValue() {
         return new Long(this.value);
     }
 
@@ -93,11 +93,9 @@ public class MutableLong extends Number implements Comparable<MutableLong>, Muta
      *            the value to set
      * @throws NullPointerException
      *             if the object is null
-     * @throws ClassCastException
-     *             if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).longValue());
+    public void setValue(Number value) {
+        this.value = value.longValue();
     }
 
     //-----------------------------------------------------------------------
@@ -258,7 +256,6 @@ public class MutableLong extends Number implements Comparable<MutableLong>, Muta
      * @param other
      *            the mutable to compare to
      * @return negative if this is less, zero if equal, positive if greater
-     * @throws ClassCastException if the argument is not a MutableLong
      */
     public int compareTo(MutableLong other) {
         long anotherVal = other.value;
diff --git a/src/java/org/apache/commons/lang/mutable/MutableShort.java b/src/java/org/apache/commons/lang/mutable/MutableShort.java
index 9e0a78919..35d222fbe 100644
--- a/src/java/org/apache/commons/lang/mutable/MutableShort.java
+++ b/src/java/org/apache/commons/lang/mutable/MutableShort.java
@@ -23,7 +23,7 @@ package org.apache.commons.lang.mutable;
  * @since 2.1
  * @version $Id$
  */
-public class MutableShort extends Number implements Comparable<MutableShort>, Mutable {
+public class MutableShort extends Number implements Comparable<MutableShort>, Mutable<Number> {
 
     /**
      * Required for serialization support.
@@ -72,7 +72,7 @@ public class MutableShort extends Number implements Comparable<MutableShort>, Mu
      * 
      * @return the value as a Short
      */
-    public Object getValue() {
+    public Short getValue() {
         return new Short(this.value);
     }
 
@@ -93,11 +93,9 @@ public class MutableShort extends Number implements Comparable<MutableShort>, Mu
      *                  the value to set
      * @throws NullPointerException
      *                  if the object is null
-     * @throws ClassCastException
-     *                  if the type is not a {@link Number}
      */
-    public void setValue(Object value) {
-        setValue(((Number) value).shortValue());
+    public void setValue(Number value) {
+        this.value = value.shortValue();
     }
 
     //-----------------------------------------------------------------------
@@ -268,7 +266,6 @@ public class MutableShort extends Number implements Comparable<MutableShort>, Mu
      * @param other
      *                  the mutable to compare to
      * @return negative if this is less, zero if equal, positive if greater
-     * @throws ClassCastException if the argument is not a MutableShort
      */
     public int compareTo(MutableShort other) {
         short anotherVal = other.value;
diff --git a/src/test/org/apache/commons/lang/mutable/MutableBooleanTest.java b/src/test/org/apache/commons/lang/mutable/MutableBooleanTest.java
index 0a25dc3c2..852e52d51 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableBooleanTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableBooleanTest.java
@@ -113,11 +113,6 @@ public class MutableBooleanTest extends TestCase {
             fail();
         } catch (NullPointerException ex) {
         }
-        try {
-            mutBool.setValue("false");
-            fail();
-        } catch (ClassCastException ex) {
-        }
     }
 
     public void testHashCode() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableByteTest.java b/src/test/org/apache/commons/lang/mutable/MutableByteTest.java
index bc046ce5b..5e67070c6 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableByteTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableByteTest.java
@@ -75,10 +75,6 @@ public class MutableByteTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testEquals() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableDoubleTest.java b/src/test/org/apache/commons/lang/mutable/MutableDoubleTest.java
index 2c37ed7cd..3f0392302 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableDoubleTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableDoubleTest.java
@@ -75,10 +75,6 @@ public class MutableDoubleTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testNanInfinite() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableFloatTest.java b/src/test/org/apache/commons/lang/mutable/MutableFloatTest.java
index 51d33ce9a..a0e7052f1 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableFloatTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableFloatTest.java
@@ -75,10 +75,6 @@ public class MutableFloatTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testNanInfinite() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableIntTest.java b/src/test/org/apache/commons/lang/mutable/MutableIntTest.java
index 4a2d03cf4..10dcb0446 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableIntTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableIntTest.java
@@ -75,10 +75,6 @@ public class MutableIntTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testEquals() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableLongTest.java b/src/test/org/apache/commons/lang/mutable/MutableLongTest.java
index 9058af829..f23413db1 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableLongTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableLongTest.java
@@ -75,10 +75,6 @@ public class MutableLongTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testEquals() {
diff --git a/src/test/org/apache/commons/lang/mutable/MutableObjectTest.java b/src/test/org/apache/commons/lang/mutable/MutableObjectTest.java
index 5b5704d62..d746d4f71 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableObjectTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableObjectTest.java
@@ -43,17 +43,17 @@ public class MutableObjectTest extends TestCase {
 
     // ----------------------------------------------------------------
     public void testConstructors() {
-        assertEquals(null, new MutableObject().getValue());
+        assertEquals(null, new MutableObject<String>().getValue());
         
         Integer i = new Integer(6);
-        assertSame(i, new MutableObject(i).getValue());
-        assertSame("HI", new MutableObject("HI").getValue());
-        assertSame(null, new MutableObject(null).getValue());
+        assertSame(i, new MutableObject<Integer>(i).getValue());
+        assertSame("HI", new MutableObject<String>("HI").getValue());
+        assertSame(null, new MutableObject<Object>(null).getValue());
     }
 
     public void testGetSet() {
-        final MutableObject mutNum = new MutableObject();
-        assertEquals(null, new MutableObject().getValue());
+        final MutableObject<String> mutNum = new MutableObject<String>();
+        assertEquals(null, new MutableObject<Object>().getValue());
         
         mutNum.setValue("HELLO");
         assertSame("HELLO", mutNum.getValue());
@@ -63,10 +63,10 @@ public class MutableObjectTest extends TestCase {
     }
 
     public void testEquals() {
-        final MutableObject mutNumA = new MutableObject("ALPHA");
-        final MutableObject mutNumB = new MutableObject("ALPHA");
-        final MutableObject mutNumC = new MutableObject("BETA");
-        final MutableObject mutNumD = new MutableObject(null);
+        final MutableObject<String> mutNumA = new MutableObject<String>("ALPHA");
+        final MutableObject<String> mutNumB = new MutableObject<String>("ALPHA");
+        final MutableObject<String> mutNumC = new MutableObject<String>("BETA");
+        final MutableObject<String> mutNumD = new MutableObject<String>(null);
 
         assertEquals(true, mutNumA.equals(mutNumA));
         assertEquals(true, mutNumA.equals(mutNumB));
@@ -84,10 +84,10 @@ public class MutableObjectTest extends TestCase {
     }
 
     public void testHashCode() {
-        final MutableObject mutNumA = new MutableObject("ALPHA");
-        final MutableObject mutNumB = new MutableObject("ALPHA");
-        final MutableObject mutNumC = new MutableObject("BETA");
-        final MutableObject mutNumD = new MutableObject(null);
+        final MutableObject<String> mutNumA = new MutableObject<String>("ALPHA");
+        final MutableObject<String> mutNumB = new MutableObject<String>("ALPHA");
+        final MutableObject<String> mutNumC = new MutableObject<String>("BETA");
+        final MutableObject<String> mutNumD = new MutableObject<String>(null);
 
         assertEquals(true, mutNumA.hashCode() == mutNumA.hashCode());
         assertEquals(true, mutNumA.hashCode() == mutNumB.hashCode());
@@ -98,9 +98,9 @@ public class MutableObjectTest extends TestCase {
     }
 
     public void testToString() {
-        assertEquals("HI", new MutableObject("HI").toString());
-        assertEquals("10.0", new MutableObject(new Double(10)).toString());
-        assertEquals("null", new MutableObject(null).toString());
+        assertEquals("HI", new MutableObject<String>("HI").toString());
+        assertEquals("10.0", new MutableObject<Double>(new Double(10)).toString());
+        assertEquals("null", new MutableObject<Object>(null).toString());
     }
 
 }
diff --git a/src/test/org/apache/commons/lang/mutable/MutableShortTest.java b/src/test/org/apache/commons/lang/mutable/MutableShortTest.java
index 7f66f6f78..497d4acc1 100644
--- a/src/test/org/apache/commons/lang/mutable/MutableShortTest.java
+++ b/src/test/org/apache/commons/lang/mutable/MutableShortTest.java
@@ -75,10 +75,6 @@ public class MutableShortTest extends TestCase {
             mutNum.setValue(null);
             fail();
         } catch (NullPointerException ex) {}
-        try {
-            mutNum.setValue("0");
-            fail();
-        } catch (ClassCastException ex) {}
     }
 
     public void testEquals() {