diff --git a/_config/config.yml b/_config/config.yml
index 8aebf73..d4bd3ea 100644
--- a/_config/config.yml
+++ b/_config/config.yml
@@ -4,6 +4,6 @@ Name: event-dispatcher-bootstrap
 SilverStripe\Core\Injector\Injector:
   SilverStripe\EventDispatcher\Dispatch\Dispatcher:
     constructor:
-      backend: %$SilverStripe\EventDispatcher\Symfony\Backend
+      backend: '%$SilverStripe\EventDispatcher\Symfony\Backend'
   SilverStripe\EventDispatcher\Event\EventContextInterface:
     class: SilverStripe\EventDispatcher\Symfony\Event