diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 0d6d7a02..e2d3a725 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@sha256:4f53136aa4bb2bfa95b0e9b8e2ce2a516301e63663887ebd727fd15b52f2043c
 FROM ghcr.io/rails/devcontainer/images/ruby:$RUBY_VERSION