diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c5d9567..750eae8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.7 ,'3.0', 3.1, 3.2, 3.3, 3.4, jruby, truffleruby]
+        ruby: [2.7 ,'3.0', 3.1, 3.2, 3.3, 3.4, 4.0, jruby, truffleruby]
 
     steps:
       - uses: actions/checkout@v4