diff --git a/.ruby-version b/.ruby-version
index 86fb65044..7919852fe 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.7
+4.0.9
diff --git a/Dockerfile b/Dockerfile
index 550f547bf..c3cb32019 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:3.3.7-slim@sha256:696f37b3cd55288b5127850e3eeae67dd20595ab77a6724f7bb05baa8c6b4878
+FROM ruby:4.0.9-slim@sha256:32fdd19c0a001077d1711f1afa6d8a0ac9d497c4eac20e47ae7e1c7f7a8c49df
 
 # Define args that can be supplied with
 # `docker build --build-args RAILS_ENV=<env>`, defaults to production.