diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1de86819..dcf2f950 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,7 +4,7 @@ on: [push]
 
 jobs:
   linting:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
 
     steps:
       - name: Pull repository
@@ -17,17 +17,26 @@ jobs:
         run: |
           bundle exec rubocop --ignore-unrecognized-cops
 
-  backend-services:
-    runs-on: ubuntu-22.04
+  tests:
+    runs-on: ubuntu-latest
+    timeout-minutes: 3
+    name: Ruby ${{ matrix.ruby }}
+    strategy:
+      matrix:
+        ruby:
+          - '3.3.12'
+          - '3.4.11'
+          - '4.0.7'
 
     steps:
       - name: Pull repository
         uses: actions/checkout@v7
-      - name: Bundle install and cache result
+      - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
+          ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
-      - name: Run rspec
+      - name: Run rspec tests
         run: |
           source .github/ci_workflow.env
           bundle exec rspec
diff --git a/.ruby-version b/.ruby-version
index a0891f56..43beb400 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.4
+4.0.7
diff --git a/Gemfile.lock b/Gemfile.lock
index dfea66ed..9c65ea1e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -106,7 +106,9 @@ GEM
       net-smtp
     method_source (1.0.0)
     mini_mime (1.1.5)
-    minitest (5.26.0)
+    minitest (6.0.6)
+      drb (~> 2.0)
+      prism (~> 1.5)
     multi_xml (0.6.0)
     mutex_m (0.3.0)
     nenv (0.3.0)
@@ -246,4 +248,4 @@ DEPENDENCIES
   webmock
 
 BUNDLED WITH
-   2.5.15
+  4.0.20
diff --git a/spec/ioki/endpoints_spec.rb b/spec/ioki/endpoints_spec.rb
index ee10da0f..3fcca5ca 100644
--- a/spec/ioki/endpoints_spec.rb
+++ b/spec/ioki/endpoints_spec.rb
@@ -18,7 +18,7 @@
 
     it 'raises an error if the argument does not respond_to the interpolation method' do
       expect { described_class.url_elements([:id], 1) }
-        .to raise_error(NoMethodError, /undefined method `id' for an instance of Integer/)
+        .to raise_error(NoMethodError, /undefined method [`']id['"]? for an instance of Integer/)
     end
 
     it 'raises an error if the path consists of something else than Strings and Symbols' do