diff --git a/spec/Prophecy/Doubler/Generator/ClassMirrorSpec.php b/spec/Prophecy/Doubler/Generator/ClassMirrorSpec.php
index cf66dc57b..de8044807 100644
--- a/spec/Prophecy/Doubler/Generator/ClassMirrorSpec.php
+++ b/spec/Prophecy/Doubler/Generator/ClassMirrorSpec.php
@@ -564,6 +564,26 @@ function it_ignores_final_methods($class, $method)
         $classNode->getMethods()->shouldHaveCount(0);
     }
 
+    /**
+     * @param ReflectionClass  $class
+     * @param ReflectionMethod $method
+     */
+    function it_marks_final_methods_as_unextendable($class, $method)
+    {
+        $class->getName()->willReturn('Custom\ClassName');
+        $class->isInterface()->willReturn(false);
+        $class->isFinal()->willReturn(false);
+        $class->getMethods(ReflectionMethod::IS_ABSTRACT)->willReturn(array());
+        $class->getMethods(ReflectionMethod::IS_PUBLIC)->willReturn(array($method));
+
+        $method->isFinal()->willReturn(true);
+        $method->getName()->willReturn('finalImplementation');
+
+        $classNode = $this->reflect($class, array());
+        $classNode->getUnextendableMethods()->shouldHaveCount(1);
+        $classNode->isExtendable('finalImplementation')->shouldReturn(false);
+    }
+
     /**
      * @param ReflectionClass $interface
      */
diff --git a/spec/Prophecy/Doubler/Generator/Node/ClassNodeSpec.php b/spec/Prophecy/Doubler/Generator/Node/ClassNodeSpec.php
index 18f0e1cc9..be7e1026e 100644
--- a/spec/Prophecy/Doubler/Generator/Node/ClassNodeSpec.php
+++ b/spec/Prophecy/Doubler/Generator/Node/ClassNodeSpec.php
@@ -3,6 +3,7 @@
 namespace spec\Prophecy\Doubler\Generator\Node;
 
 use PhpSpec\ObjectBehavior;
+use Prophecy\Exception\Doubler\MethodNotExtendableException;
 
 class ClassNodeSpec extends ObjectBehavior
 {
@@ -151,4 +152,49 @@ function its_addProperty_lowercases_visibility_before_setting()
         $this->addProperty('text', 'PRIVATE');
         $this->getProperties()->shouldReturn(array('text' => 'private'));
     }
+
+    function its_has_no_unextendable_methods_by_default()
+    {
+        $this->getUnextendableMethods()->shouldHaveCount(0);
+    }
+
+    function its_addUnextendableMethods_adds_an_unextendable_method()
+    {
+        $this->addUnextendableMethod('testMethod');
+        $this->getUnextendableMethods()->shouldHaveCount(1);
+    }
+
+    function its_methods_are_extendable_by_default()
+    {
+        $this->isExtendable('testMethod')->shouldReturn(true);
+    }
+
+    function its_unextendable_methods_are_not_extendable()
+    {
+        $this->addUnextendableMethod('testMethod');
+        $this->isExtendable('testMethod')->shouldReturn(false);
+    }
+
+    function its_addUnextendableMethods_doesnt_create_duplicates()
+    {
+        $this->addUnextendableMethod('testMethod');
+        $this->addUnextendableMethod('testMethod');
+        $this->getUnextendableMethods()->shouldHaveCount(1);
+    }
+
+    /**
+     * @param \Prophecy\Doubler\Generator\Node\MethodNode $method
+     */
+    function it_throws_an_exception_when_adding_a_method_that_isnt_extendable($method)
+    {
+        $this->addUnextendableMethod('testMethod');
+        $method->getName()->willReturn('testMethod');
+
+        $expectedException = new MethodNotExtendableException(
+            "Method `testMethod` is not extendable, so can not be added.",
+            "stdClass",
+            "testMethod"
+        );
+        $this->shouldThrow($expectedException)->duringAddMethod($method);
+    }
 }
diff --git a/spec/Prophecy/Exception/Doubler/MethodNotExtendableExceptionSpec.php b/spec/Prophecy/Exception/Doubler/MethodNotExtendableExceptionSpec.php
new file mode 100644
index 000000000..5028b0263
--- /dev/null
+++ b/spec/Prophecy/Exception/Doubler/MethodNotExtendableExceptionSpec.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace spec\Prophecy\Exception\Doubler;
+
+use PhpSpec\ObjectBehavior;
+use spec\Prophecy\Exception\Prophecy;
+
+class MethodNotExtendableExceptionSpec extends ObjectBehavior
+{
+    function let()
+    {
+        $this->beConstructedWith('', 'User', 'getName');
+    }
+
+    function it_is_DoubleException()
+    {
+        $this->shouldHaveType('Prophecy\Exception\Doubler\DoubleException');
+    }
+
+    function it_has_MethodName()
+    {
+        $this->getMethodName()->shouldReturn('getName');
+    }
+
+    function it_has_classname()
+    {
+        $this->getClassName()->shouldReturn('User');
+    }
+}
diff --git a/src/Prophecy/Doubler/Generator/ClassMirror.php b/src/Prophecy/Doubler/Generator/ClassMirror.php
index af2bd6706..acdb2c15b 100644
--- a/src/Prophecy/Doubler/Generator/ClassMirror.php
+++ b/src/Prophecy/Doubler/Generator/ClassMirror.php
@@ -110,6 +110,7 @@ private function reflectClassToNode(ReflectionClass $class, Node\ClassNode $node
             }
 
             if (true === $method->isFinal()) {
+                $node->addUnextendableMethod($method->getName());
                 continue;
             }
 
diff --git a/src/Prophecy/Doubler/Generator/Node/ClassNode.php b/src/Prophecy/Doubler/Generator/Node/ClassNode.php
index b38cb4ea3..1499a1d32 100644
--- a/src/Prophecy/Doubler/Generator/Node/ClassNode.php
+++ b/src/Prophecy/Doubler/Generator/Node/ClassNode.php
@@ -11,6 +11,7 @@
 
 namespace Prophecy\Doubler\Generator\Node;
 
+use Prophecy\Exception\Doubler\MethodNotExtendableException;
 use Prophecy\Exception\InvalidArgumentException;
 
 /**
@@ -23,6 +24,7 @@ class ClassNode
     private $parentClass = 'stdClass';
     private $interfaces  = array();
     private $properties  = array();
+    private $unextendableMethods = array();
 
     /**
      * @var MethodNode[]
@@ -100,6 +102,12 @@ public function getMethods()
 
     public function addMethod(MethodNode $method)
     {
+        if (!$this->isExtendable($method->getName())){
+            $message = sprintf(
+                'Method `%s` is not extendable, so can not be added.', $method->getName()
+            );
+            throw new MethodNotExtendableException($message, $this->getParentClass(), $method->getName());
+        }
         $this->methods[$method->getName()] = $method;
     }
 
@@ -127,4 +135,32 @@ public function hasMethod($name)
     {
         return isset($this->methods[$name]);
     }
+
+    /**
+     * @return string[]
+     */
+    public function getUnextendableMethods()
+    {
+        return $this->unextendableMethods;
+    }
+
+    /**
+     * @param string $unextendableMethod
+     */
+    public function addUnextendableMethod($unextendableMethod)
+    {
+        if (!$this->isExtendable($unextendableMethod)){
+            return;
+        }
+        $this->unextendableMethods[] = $unextendableMethod;
+    }
+
+    /**
+     * @param string $method
+     * @return bool
+     */
+    public function isExtendable($method)
+    {
+        return !in_array($method, $this->unextendableMethods);
+    }
 }
diff --git a/src/Prophecy/Exception/Doubler/MethodNotExtendableException.php b/src/Prophecy/Exception/Doubler/MethodNotExtendableException.php
new file mode 100644
index 000000000..8437dc2ef
--- /dev/null
+++ b/src/Prophecy/Exception/Doubler/MethodNotExtendableException.php
@@ -0,0 +1,47 @@
+<?php
+    /**
+     * Created by PhpStorm.
+     * User: jeff
+     * Date: 25/08/2015
+     * Time: 19:14
+     */
+
+    namespace Prophecy\Exception\Doubler;
+
+    class MethodNotExtendableException extends DoubleException
+    {
+        private $methodName;
+
+        private $className;
+
+        /**
+         * @param string $message
+         * @param string $className
+         * @param string $methodName
+         */
+        public function __construct($message, $className, $methodName)
+        {
+            parent::__construct($message);
+
+            $this->methodName = $methodName;
+            $this->className = $className;
+        }
+
+
+        /**
+         * @return string
+         */
+        public function getMethodName()
+        {
+            return $this->methodName;
+        }
+
+        /**
+         * @return string
+         */
+        public function getClassName()
+        {
+            return $this->className;
+        }
+
+    }