diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8cea3e2f0..113dea88a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,12 +27,11 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
+        - '4.0'
         - '3.4'
         - '3.3'
-        - '3.2'
-        - '3.1'
         include:
-        - ruby: '3.4'
+        - ruby: '4.0'
           use_dry_transformer_master: 'true'
           use_dry_initializer_main: 'true'
     env:
diff --git a/Gemfile b/Gemfile
index cf96b260e..af91a3d40 100644
--- a/Gemfile
+++ b/Gemfile
@@ -43,6 +43,7 @@ end
 
 group :test do
   gem 'codacy-coverage', require: false
+  gem 'ostruct'
   gem 'rspec', '~> 3.6'
   gem 'simplecov', platforms: :ruby
   gem 'warning'
diff --git a/core/spec/unit/rom/schema_spec.rb b/core/spec/unit/rom/schema_spec.rb
index 0092b8c93..4aa7cef3d 100644
--- a/core/spec/unit/rom/schema_spec.rb
+++ b/core/spec/unit/rom/schema_spec.rb
@@ -25,8 +25,8 @@
       expect(schema.to_ast)
         .to eql([:schema, [
           :name,
-          [[:attribute, [:id, [:nominal, [Integer, {}]], alias: nil]],
-           [:attribute, [:name, [:nominal, [String, {}]], alias: nil]]]
+          [[:attribute, [:id, [:nominal, [Integer, {}, {}]], alias: nil]],
+           [:attribute, [:name, [:nominal, [String, {}, {}]], alias: nil]]]
         ]])
     end
   end