diff --git a/composer.lock b/composer.lock
index de2023bbf873..d0fc6f6076cc 100644
--- a/composer.lock
+++ b/composer.lock
@@ -685,7 +685,7 @@
         },
         {
             "name": "drupal/core",
-            "version": "8.9.x-dev",
+            "version": "9.0.x-dev",
             "dist": {
                 "type": "path",
                 "url": "core",
diff --git a/core/lib/Drupal.php b/core/lib/Drupal.php
index 974f4e03ac8c..e1ae1ba09d83 100644
--- a/core/lib/Drupal.php
+++ b/core/lib/Drupal.php
@@ -82,7 +82,7 @@ class Drupal {
   /**
    * The current system version.
    */
-  const VERSION = '8.9.0-dev';
+  const VERSION = '9.0.0-dev';
 
   /**
    * Core API compatibility.