diff --git a/.rubocop.yml b/.rubocop.yml
index 62a1484..8754ade 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -4,9 +4,9 @@ AllCops:
   Include:
     - 'lib/**/*.rb'
     - 'modules/**/*.rb'
-  TargetRubyVersion: 3.3.0
+  TargetRubyVersion: 4.0
 
-require:
+plugins:
   - rubocop-minitest
 
 Style/FrozenStringLiteralComment:
@@ -26,5 +26,8 @@ Metrics/MethodLength:
 Style/EachWithObject:
   Enabled: false
 
+Style/ReduceToHash:
+  Enabled: false
+
 Style/AsciiComments:
   Enabled: false
diff --git a/Dockerfile b/Dockerfile
index f7cffd6..6c7cb54 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,12 +1,12 @@
+FROM ruby:4.0-slim-bookworm AS ruby-source
 FROM hexletbasics/base-image:latest
 
+COPY --from=ruby-source /usr/local /usr/local
+
 ENV RUBYLIB=/exercises-ruby/lib
 ENV PATH=/exercises-ruby/bin:$PATH
 
-RUN apt-get update && \
-    apt-get install -y ruby-full bundler && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
+RUN gem install bundler
 
 WORKDIR /exercises-ruby