diff --git a/.ruby-version b/.ruby-version
index 2aa51319..c4e41f94 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.7
+4.0.3
diff --git a/Dockerfile b/Dockerfile
index ad42fc43..4622297e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 
-FROM ruby:3.4.7-alpine@sha256:d279decff1a40535597120bf9546b6c01a5d00298b9a87628f28cf0efd07b02c
+FROM ruby:4.0.3-alpine@sha256:2c041dcda87517d61ecd3b65832e6433384f8bdfec5b49d07de7f9a84e94f09b
 
 ARG BUILD_HASH='unknown'
 ENV BUILD_HASH=$BUILD_HASH