diff --git a/.ruby-version b/.ruby-version
index 1454f6e..c4e41f9 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-4.0.1
+4.0.3
diff --git a/Dockerfile b/Dockerfile
index 9a13ca4..7084360 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -8,7 +8,7 @@
 # For a containerized dev environment, see Dev Containers: https://guides.rubyonrails.org/getting_started_with_devcontainer.html
 
 # Make sure RUBY_VERSION matches the Ruby version in .ruby-version
-ARG RUBY_VERSION=4.0.1
+ARG RUBY_VERSION=4.0.3
 FROM docker.io/library/ruby:$RUBY_VERSION-slim AS base
 
 LABEL org.opencontainers.image.source=https://github.com/dkam/clinch