diff --git a/.ruby-version b/.ruby-version
index 2aa51319..7636e756 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.7
+4.0.5
diff --git a/Dockerfile b/Dockerfile
index ad42fc43..c4a614bc 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 
-FROM ruby:3.4.7-alpine@sha256:d279decff1a40535597120bf9546b6c01a5d00298b9a87628f28cf0efd07b02c
+FROM ruby:4.0.5-alpine@sha256:378d06a06edb7e90ed4deef6293129729203b232283c2ecf62f066e17fab10e6
 
 ARG BUILD_HASH='unknown'
 ENV BUILD_HASH=$BUILD_HASH