diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 3293527..8eac4dd 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -23,7 +23,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby-version: ['3.2', '3.3', '3.4', head, jruby, jruby-head]
+        ruby-version: ['3.2', '3.3', '3.4', '4.0', head, jruby, jruby-head]
 
     steps:
     - uses: actions/checkout@v4