diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 3f811317..2b92d11c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,8 +1,8 @@
 name: Main
 
 on:
-- push
-- pull_request
+  - push
+  - pull_request
 
 jobs:
   ci:
@@ -10,25 +10,35 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
-        - '2.7.0'
-        - '3.0'
-        - '3.1'
-        - '3.2'
-        - head
-        - truffleruby-head
+          - "3.2"
+          - "3.3"
+          - head
+        rubyopt:
+          - ""
+          - "--yjit"
+          - "--enable=frozen-string-literal"
+        include:
+          - ruby: "2.7"
+            rubyopt: ""
+          - ruby: "2.7"
+            rubyopt: "--enable=frozen-string-literal"
+          # - ruby: truffleruby-head
+
     name: CI
     runs-on: ubuntu-latest
     env:
       CI: true
       # TESTOPTS: --verbose
     steps:
-    - uses: actions/checkout@master
-    - uses: ruby/setup-ruby@v1
-      with:
-        bundler-cache: true
-        ruby-version: ${{ matrix.ruby }}
-    - name: Test
-      run: bundle exec rake test
+      - uses: actions/checkout@master
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+          ruby-version: ${{ matrix.ruby }}
+      - name: Test
+        run: bundle exec rake test
+        env:
+          RUBYOPT: ${{ matrix.rubyopt }}
 
   check:
     name: Check
@@ -36,12 +46,11 @@ jobs:
     env:
       CI: true
     steps:
-    - uses: actions/checkout@master
-    - uses: ruby/setup-ruby@v1
-      with:
-        bundler-cache: true
-        ruby-version: '3.2'
-    - name: Check
-      run: |
-        bundle exec rake stree:check
-        bundle exec rubocop
+      - uses: actions/checkout@master
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+      - name: Check
+        run: |
+          bundle exec rake stree:check
+          bundle exec rubocop
diff --git a/.ruby-version b/.ruby-version
index 944880fa..9c25013d 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.2.0
+3.3.6