diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 0d6d7a02..521201ff 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=3.4.7@sha256:9fd34eafd04b1f54b4e939f5b8c6fb9988d592699082e087aff6c27a7af1e2dc
 FROM ghcr.io/rails/devcontainer/images/ruby:$RUBY_VERSION