diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eb3ad4526..5cbc67acd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,7 +19,7 @@ jobs:
         uses: ruby/setup-ruby@80740b3b13bf9857e28854481ca95a84e78a2bdf # v1.284.0
         with:
           bundler-cache: true
-          rubygems: 3.6.2
+          rubygems: 4.0.4
       - name: Run type check
         run: bin/typecheck
       - name: Run type check with Prism parser
diff --git a/.ruby-version b/.ruby-version
index fcdb2e109..1454f6ed4 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-4.0.0
+4.0.1