diff --git a/composer.json b/composer.json
index 444668b..dd6ddb2 100644
--- a/composer.json
+++ b/composer.json
@@ -31,6 +31,7 @@
                 "beet_site_name": "Drupal 8 Sprint Box",
                 "drupal_create_makefile": true,
                 "drupal_make_working_copy": true,
+                "drupal_make_core_branch": "8.4.x",
                 "drupal_build_makefile": true,
                 "drupal_install_site": true,
                 "drupal_account_name": "admin",
diff --git a/composer.lock b/composer.lock
index de04004..8f06192 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": "a1a732c64c5995fa56cfaaae8e90ecb5",
+    "content-hash": "5ddce56a30093ab69f2ec9495ecbe804",
     "packages": [],
     "packages-dev": [
         {