diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 0d6d7a02..b0c774cc 100644
--- a/.devcontainer/Dockerfile
+++ b/.devcontainer/Dockerfile
@@ -1,3 +1,3 @@
 # Make sure RUBY_VERSION matches the Ruby version in .ruby-version
-ARG RUBY_VERSION=3.4.7
+ARG RUBY_VERSION=4.0.1@sha256:f1d59e565f58c2ce42a88b9f137ca4d9da739c0baa4401f75d3807f2241241b8
 FROM ghcr.io/rails/devcontainer/images/ruby:$RUBY_VERSION