diff --git a/.rubocop.yml b/.rubocop.yml
index ca62dc38..29d9da9d 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -7,7 +7,7 @@ require:
   - rubocop-factory_bot
 
 AllCops:
-  TargetRubyVersion: 3.3
+  TargetRubyVersion: 3.4
   Exclude:
     - app/frontend/**/*
     - bin/**/*
diff --git a/.ruby-version b/.ruby-version
index 9c25013d..47b322c9 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.6
+3.4.1
diff --git a/Dockerfile b/Dockerfile
index 75e601e2..27ad512f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,10 +1,10 @@
-FROM ghcr.io/ledermann/rails-base-builder:3.3.6-alpine AS builder
+FROM ghcr.io/ledermann/rails-base-builder:3.4.1-alpine AS builder
 
 # Remove some files not needed in resulting image.
 # Because they are required for building the image, they can't be added to .dockerignore
 RUN rm -r package.json tailwind.config.js postcss.config.js vite.config.mts tsconfig.json
 
-FROM ghcr.io/ledermann/rails-base-final:3.3.6-alpine
+FROM ghcr.io/ledermann/rails-base-final:3.4.1-alpine
 LABEL maintainer="georg@ledermann.dev"
 
 # Workaround to trigger builder's ONBUILDs to finish:
diff --git a/Gemfile.lock b/Gemfile.lock
index 79f1b533..ad964ad7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -130,9 +130,7 @@ GEM
     factory_bot_rails (6.4.4)
       factory_bot (~> 6.5)
       railties (>= 5.0.0)
-    ffi (1.17.0-arm64-darwin)
-    ffi (1.17.0-x86_64-linux-gnu)
-    ffi (1.17.0-x86_64-linux-musl)
+    ffi (1.17.0)
     formatador (1.1.0)
     globalid (1.2.1)
       activesupport (>= 6.1)
@@ -208,7 +206,6 @@ GEM
     net-protocol (0.2.2)
       timeout
     net-smtp (0.5.0)
-      net-protocol
     nio4r (2.7.4)
     nokogiri (1.18.0-arm64-darwin)
       racc (~> 1.4)
@@ -459,7 +456,7 @@ DEPENDENCIES
   web-console (>= 4.1.0)
 
 RUBY VERSION
-   ruby 3.3.6p108
+   ruby 3.4.1p0
 
 BUNDLED WITH
    2.6.2
diff --git a/README.md b/README.md
index a7f71466..8450f9b0 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ There are two sister repositories:
 
 ### Backend
 
-- [Ruby](https://www.ruby-lang.org/de/) 3.3
+- [Ruby](https://www.ruby-lang.org/de/) 3.4
 - [Ruby on Rails](https://rubyonrails.org/) 8.0
 - [ActionCable](https://guides.rubyonrails.org/action_cable_overview.html) for WebSocket communication
 - [PostgreSQL](https://www.postgresql.org/) for using as SQL database