diff --git a/.cow.json b/.cow.json
index e2bc3260..ebfbfd0a 100644
--- a/.cow.json
+++ b/.cow.json
@@ -3,8 +3,7 @@
   "child-stability-inherit": true,
   "dependency-constraint": "loose",
   "vendors": [
-    "silverstripe",
-    "silverstripe-themes"
+    "silverstripe"
   ],
   "tests": [
     "vendor/bin/phpunit vendor/silverstripe/framework/tests/php",
diff --git a/app/_config/theme.yml b/app/_config/theme.yml
index e1184e7e..f4df9e41 100755
--- a/app/_config/theme.yml
+++ b/app/_config/theme.yml
@@ -4,5 +4,5 @@ Name: mytheme
 SilverStripe\View\SSViewer:
   themes:
     - '$public'
-    - 'simple'
+    - 'startup-theme'
     - '$default'
diff --git a/composer.json b/composer.json
index c8bc8606..be365590 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
         "silverstripe/recipe-plugin": "2.0.x-dev",
         "silverstripe/vendor-plugin": "3.0.x-dev",
         "silverstripe/recipe-cms": "6.0.x-dev",
-        "silverstripe-themes/simple": "3.3.x-dev",
+        "silverstripe/startup-theme": "1.0.x-dev",
         "silverstripe/login-forms": "6.0.x-dev"
     },
     "require-dev": {