diff --git a/composer.json b/composer.json
index b9536cfe35c..97c131f9c4e 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
         "wikimedia/composer-merge-plugin": "^1.4"
     },
     "replace": {
-        "drupal/core": "^8.4"
+        "drupal/core": "^8.5"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
diff --git a/composer.lock b/composer.lock
index 6622a70a91f..310254b2e0e 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "bec46eaaa9fa07a4cbd8c84302f0d275",
+    "content-hash": "97de1708c79f6205a295cfc9808c0c72",
     "packages": [
         {
             "name": "asm89/stack-cors",
diff --git a/core/lib/Drupal.php b/core/lib/Drupal.php
index 1acfc12e9a6..07dc12f1f31 100644
--- a/core/lib/Drupal.php
+++ b/core/lib/Drupal.php
@@ -81,7 +81,7 @@ class Drupal {
   /**
    * The current system version.
    */
-  const VERSION = '8.4.0-dev';
+  const VERSION = '8.5.0-dev';
 
   /**
    * Core API compatibility.