diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 13a3aac..f79f176 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -24,6 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
+          - '4.0'
           - 3.4
           - 3.3
           - 3.2