diff --git a/.ruby-version b/.ruby-version
index 86fb65044..c4e41f945 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.7
+4.0.3
diff --git a/Dockerfile b/Dockerfile
index 550f547bf..8ddf6b451 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:3.3.7-slim@sha256:696f37b3cd55288b5127850e3eeae67dd20595ab77a6724f7bb05baa8c6b4878
+FROM ruby:4.0.3-slim@sha256:0b3d0a3854498216a3c30586a2da996734b18112f2a024c9939651d02cad1745
 
 # Define args that can be supplied with
 # `docker build --build-args RAILS_ENV=<env>`, defaults to production.