diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 63fa0ad..df5ea1e 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ['3.0', '3.1', '3.2', '3.3']
+        ruby: ['3.0', '3.1', '3.2', '3.3', '3.4']
     steps:
     - uses: actions/checkout@v4
     - name: Set up Ruby
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc0bc36..726e51a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 ## Unreleased
 
+### Misc
+
+* CI against for Ruby 3.4
+
 
 ## 2.1.0 (2023-12-25)
 
diff --git a/spec/recite_csv/header/definition_spec.rb b/spec/recite_csv/header/definition_spec.rb
index 0e478ce..0079135 100644
--- a/spec/recite_csv/header/definition_spec.rb
+++ b/spec/recite_csv/header/definition_spec.rb
@@ -14,7 +14,7 @@
     end
 
     context "pass a subclass object of hash" do
-      let(:object) { Class.new(Hash).new(col1: "COL1", col2: "COL2") }
+      let(:object) { Class.new(Hash).new({ col1: "COL1", col2: "COL2" }) }
       it { is_expected.to be_a ReciteCSV::Header::Definition::Hash }
     end