diff --git a/src/Symfony/Component/Workflow/Definition.php b/src/Symfony/Component/Workflow/Definition.php
index 52e1d1ee4c042..c1bce17373196 100644
--- a/src/Symfony/Component/Workflow/Definition.php
+++ b/src/Symfony/Component/Workflow/Definition.php
@@ -18,7 +18,7 @@
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Grégoire Pineau <lyrixx@lyrixx.info>
  */
-class Definition
+class Definition implements DefinitionInterface
 {
     private $places = array();
     private $transitions = array();
diff --git a/src/Symfony/Component/Workflow/DefinitionInterface.php b/src/Symfony/Component/Workflow/DefinitionInterface.php
new file mode 100644
index 0000000000000..118242696b5e5
--- /dev/null
+++ b/src/Symfony/Component/Workflow/DefinitionInterface.php
@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Workflow;
+
+/**
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+interface DefinitionInterface
+{
+    /**
+     * Get the initial place.
+     *
+     * @return string
+     */
+    public function getInitialPlace();
+
+    /**
+     * Get all the places.
+     *
+     * @return string[]
+     */
+    public function getPlaces();
+
+    /**
+     * @return Transition[]
+     */
+    public function getTransitions();
+}
diff --git a/src/Symfony/Component/Workflow/Dumper/DumperInterface.php b/src/Symfony/Component/Workflow/Dumper/DumperInterface.php
index b0eebd34f1952..1dd9492273ec2 100644
--- a/src/Symfony/Component/Workflow/Dumper/DumperInterface.php
+++ b/src/Symfony/Component/Workflow/Dumper/DumperInterface.php
@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Workflow\Dumper;
 
-use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 use Symfony\Component\Workflow\Marking;
 
 /**
@@ -25,11 +25,11 @@ interface DumperInterface
     /**
      * Dumps a workflow definition.
      *
-     * @param Definition   $definition A Definition instance
-     * @param Marking|null $marking    A Marking instance
-     * @param array        $options    An array of options
+     * @param DefinitionInterface $definition A Definition instance
+     * @param Marking|null        $marking    A Marking instance
+     * @param array               $options    An array of options
      *
      * @return string The representation of the workflow
      */
-    public function dump(Definition $definition, Marking $marking = null, array $options = array());
+    public function dump(DefinitionInterface $definition, Marking $marking = null, array $options = array());
 }
diff --git a/src/Symfony/Component/Workflow/Dumper/GraphvizDumper.php b/src/Symfony/Component/Workflow/Dumper/GraphvizDumper.php
index 916c4bd460622..8ae079bcb865d 100644
--- a/src/Symfony/Component/Workflow/Dumper/GraphvizDumper.php
+++ b/src/Symfony/Component/Workflow/Dumper/GraphvizDumper.php
@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Workflow\Dumper;
 
-use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 use Symfony\Component\Workflow\Marking;
 
 /**
@@ -43,7 +43,7 @@ class GraphvizDumper implements DumperInterface
      *  * node: The default options for nodes (places + transitions)
      *  * edge: The default options for edges
      */
-    public function dump(Definition $definition, Marking $marking = null, array $options = array())
+    public function dump(DefinitionInterface $definition, Marking $marking = null, array $options = array())
     {
         $places = $this->findPlaces($definition, $marking);
         $transitions = $this->findTransitions($definition);
@@ -58,7 +58,7 @@ public function dump(Definition $definition, Marking $marking = null, array $opt
             .$this->endDot();
     }
 
-    private function findPlaces(Definition $definition, Marking $marking = null)
+    private function findPlaces(DefinitionInterface $definition, Marking $marking = null)
     {
         $places = array();
 
@@ -79,7 +79,7 @@ private function findPlaces(Definition $definition, Marking $marking = null)
         return $places;
     }
 
-    private function findTransitions(Definition $definition)
+    private function findTransitions(DefinitionInterface $definition)
     {
         $transitions = array();
 
@@ -123,7 +123,7 @@ private function addTransitions(array $transitions)
         return $code;
     }
 
-    private function findEdges(Definition $definition)
+    private function findEdges(DefinitionInterface $definition)
     {
         $dotEdges = array();
 
diff --git a/src/Symfony/Component/Workflow/StateMachine.php b/src/Symfony/Component/Workflow/StateMachine.php
index 0c4e3edc0a6b5..5fc0be74e164d 100644
--- a/src/Symfony/Component/Workflow/StateMachine.php
+++ b/src/Symfony/Component/Workflow/StateMachine.php
@@ -11,7 +11,7 @@
  */
 class StateMachine extends Workflow
 {
-    public function __construct(Definition $definition, MarkingStoreInterface $markingStore = null, EventDispatcherInterface $dispatcher = null, $name = 'unnamed')
+    public function __construct(DefinitionInterface $definition, MarkingStoreInterface $markingStore = null, EventDispatcherInterface $dispatcher = null, $name = 'unnamed')
     {
         parent::__construct($definition, $markingStore ?: new ScalarMarkingStore(), $dispatcher, $name);
     }
diff --git a/src/Symfony/Component/Workflow/Validator/DefinitionValidatorInterface.php b/src/Symfony/Component/Workflow/Validator/DefinitionValidatorInterface.php
index 09fbc706c74bd..77a73696bf592 100644
--- a/src/Symfony/Component/Workflow/Validator/DefinitionValidatorInterface.php
+++ b/src/Symfony/Component/Workflow/Validator/DefinitionValidatorInterface.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Workflow\Validator;
 
 use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 use Symfony\Component\Workflow\Exception\InvalidDefinitionException;
 
 /**
@@ -20,12 +21,12 @@
 interface DefinitionValidatorInterface
 {
     /**
-     * @param Definition $definition
-     * @param string     $name
+     * @param DefinitionInterface $definition
+     * @param string              $name
      *
      * @return bool
      *
      * @throws InvalidDefinitionException on invalid definition
      */
-    public function validate(Definition $definition, $name);
+    public function validate(DefinitionInterface $definition, $name);
 }
diff --git a/src/Symfony/Component/Workflow/Validator/SinglePlaceWorkflowValidator.php b/src/Symfony/Component/Workflow/Validator/SinglePlaceWorkflowValidator.php
index 6b59db507dff9..61c4bc7c6b827 100644
--- a/src/Symfony/Component/Workflow/Validator/SinglePlaceWorkflowValidator.php
+++ b/src/Symfony/Component/Workflow/Validator/SinglePlaceWorkflowValidator.php
@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Workflow\Validator;
 
-use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 use Symfony\Component\Workflow\Exception\InvalidDefinitionException;
 
 /**
@@ -21,7 +21,7 @@
  */
 class SinglePlaceWorkflowValidator extends WorkflowValidator
 {
-    public function validate(Definition $definition, $name)
+    public function validate(DefinitionInterface $definition, $name)
     {
         foreach ($definition->getTransitions() as $transition) {
             if (1 < count($transition->getTos())) {
diff --git a/src/Symfony/Component/Workflow/Validator/StateMachineValidator.php b/src/Symfony/Component/Workflow/Validator/StateMachineValidator.php
index 6f34c1f2f41ab..e4f29281dc479 100644
--- a/src/Symfony/Component/Workflow/Validator/StateMachineValidator.php
+++ b/src/Symfony/Component/Workflow/Validator/StateMachineValidator.php
@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Workflow\Validator;
 
-use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 use Symfony\Component\Workflow\Exception\InvalidDefinitionException;
 
 /**
@@ -19,7 +19,7 @@
  */
 class StateMachineValidator implements DefinitionValidatorInterface
 {
-    public function validate(Definition $definition, $name)
+    public function validate(DefinitionInterface $definition, $name)
     {
         $transitionFromNames = array();
         foreach ($definition->getTransitions() as $transition) {
diff --git a/src/Symfony/Component/Workflow/Validator/WorkflowValidator.php b/src/Symfony/Component/Workflow/Validator/WorkflowValidator.php
index 7d4366fdfb9c3..a4c5e207ad2af 100644
--- a/src/Symfony/Component/Workflow/Validator/WorkflowValidator.php
+++ b/src/Symfony/Component/Workflow/Validator/WorkflowValidator.php
@@ -11,14 +11,14 @@
 
 namespace Symfony\Component\Workflow\Validator;
 
-use Symfony\Component\Workflow\Definition;
+use Symfony\Component\Workflow\DefinitionInterface;
 
 /**
  * @author Tobias Nyholm <tobias.nyholm@gmail.com>
  */
 class WorkflowValidator implements DefinitionValidatorInterface
 {
-    public function validate(Definition $definition, $name)
+    public function validate(DefinitionInterface $definition, $name)
     {
     }
 }
diff --git a/src/Symfony/Component/Workflow/Workflow.php b/src/Symfony/Component/Workflow/Workflow.php
index 348b3b95a9a98..e8cefd8009304 100644
--- a/src/Symfony/Component/Workflow/Workflow.php
+++ b/src/Symfony/Component/Workflow/Workflow.php
@@ -30,7 +30,7 @@ class Workflow
     private $dispatcher;
     private $name;
 
-    public function __construct(Definition $definition, MarkingStoreInterface $markingStore = null, EventDispatcherInterface $dispatcher = null, $name = 'unnamed')
+    public function __construct(DefinitionInterface $definition, MarkingStoreInterface $markingStore = null, EventDispatcherInterface $dispatcher = null, $name = 'unnamed')
     {
         $this->definition = $definition;
         $this->markingStore = $markingStore ?: new PropertyAccessorMarkingStore();