diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4ad1da24..d97837e7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,11 +36,12 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
+          - '4.0'
           - '3.4'
           - '3.3'
           - '3.2'
         include:
-          - ruby: '3.4'
+          - ruby: '4.0'
             coverage: 'true'
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
@@ -95,11 +96,12 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
+          - '4.0'
           - '3.4'
           - '3.3'
           - '3.2'
         include:
-          - ruby: '3.4'
+          - ruby: '4.0'
             coverage: 'true'
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
diff --git a/v2.5-non-rails/.ruby-version b/v2.5-non-rails/.ruby-version
index 2aa51319..fcdb2e10 100644
--- a/v2.5-non-rails/.ruby-version
+++ b/v2.5-non-rails/.ruby-version
@@ -1 +1 @@
-3.4.7
+4.0.0
diff --git a/v2.5-non-rails/Gemfile b/v2.5-non-rails/Gemfile
index 7c225b63..7cbcf26b 100644
--- a/v2.5-non-rails/Gemfile
+++ b/v2.5-non-rails/Gemfile
@@ -4,6 +4,7 @@ source 'https://rubygems.org'
 
 # ActiveSupport and rexml are only used for XML support
 gem 'activesupport'
+gem 'ostruct'
 gem 'rake'
 gem 'rexml'
 
diff --git a/v2.5-non-rails/Gemfile.lock b/v2.5-non-rails/Gemfile.lock
index eb3c49bc..e78e6da5 100644
--- a/v2.5-non-rails/Gemfile.lock
+++ b/v2.5-non-rails/Gemfile.lock
@@ -81,6 +81,7 @@ GEM
     logger (1.7.0)
     mini_portile2 (2.8.9)
     minitest (5.27.0)
+    ostruct (0.6.3)
     rake (13.3.1)
     rexml (3.4.4)
     rspec (3.13.2)
@@ -130,6 +131,7 @@ DEPENDENCIES
   byebug
   karafka
   karafka-testing
+  ostruct
   rake
   rexml
   rspec
diff --git a/v2.5-rails/.ruby-version b/v2.5-rails/.ruby-version
index 2aa51319..fcdb2e10 100644
--- a/v2.5-rails/.ruby-version
+++ b/v2.5-rails/.ruby-version
@@ -1 +1 @@
-3.4.7
+4.0.0
diff --git a/v2.5-rails/Gemfile b/v2.5-rails/Gemfile
index 07b77539..608bb96d 100644
--- a/v2.5-rails/Gemfile
+++ b/v2.5-rails/Gemfile
@@ -4,6 +4,7 @@ source 'https://rubygems.org'
 
 gem 'karafka'
 gem 'karafka-web'
+gem 'ostruct'
 gem 'puma'
 gem 'rails', '~> 8.0'
 gem 'sqlite3', '2.8.1'
diff --git a/v2.5-rails/Gemfile.lock b/v2.5-rails/Gemfile.lock
index 9bc8ab00..9c7b3b8d 100644
--- a/v2.5-rails/Gemfile.lock
+++ b/v2.5-rails/Gemfile.lock
@@ -198,6 +198,7 @@ GEM
       racc (~> 1.4)
     nokogiri (1.18.10-x86_64-linux-musl)
       racc (~> 1.4)
+    ostruct (0.6.3)
     pp (0.6.3)
       prettyprint
     prettyprint (0.2.0)
@@ -316,6 +317,7 @@ DEPENDENCIES
   karafka
   karafka-testing
   karafka-web
+  ostruct
   puma
   rails (~> 8.0)
   rspec