diff --git a/demo/kuby.rb b/demo/kuby.rb
index b9e2ef4834..b76f6a85d1 100644
--- a/demo/kuby.rb
+++ b/demo/kuby.rb
@@ -42,6 +42,8 @@ def install_from_image(image, dockerfile)
         password ENV["AZURE_ACR_PASSWORD"]
       end
 
+      setup_phase.base_image = "ruby:3.3"
+
       image_url ENV["IMAGE_URL"] || "primer.azurecr.io/primer/view_components_storybook"
 
       # Run bundler, npm, etc in this directory.