diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 571be03..53fe035 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -18,7 +18,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: ["3.2", "3.3", "3.4"]
+        ruby: ["3.2", "3.3", "3.4", "4.0"]
 
     steps:
       - uses: actions/checkout@v6