diff --git a/src/Symfony/Component/Workflow/Workflow.php b/src/Symfony/Component/Workflow/Workflow.php
index e3df8cb0d072..76e53eda5120 100644
--- a/src/Symfony/Component/Workflow/Workflow.php
+++ b/src/Symfony/Component/Workflow/Workflow.php
@@ -43,7 +43,7 @@ public function __construct(Definition $definition, MarkingStoreInterface $marki
     {
         $this->definition = $definition;
         $this->markingStore = $markingStore ?: new MultipleStateMarkingStore();
-        $this->dispatcher = LegacyEventDispatcherProxy::decorate($dispatcher);
+        $this->dispatcher = null !== $dispatcher ? LegacyEventDispatcherProxy::decorate($dispatcher) : null;
         $this->name = $name;
     }