diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 40c6f9d..2010c7f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,6 +13,7 @@ jobs:
           - '3.2'
           - '3.3'
           - '3.4'
+          - 'head'
           - 'jruby-9.4'
         gemfile:
           - rails7.0
diff --git a/gemfiles/common.rb b/gemfiles/common.rb
index acdc138..b2e6c7b 100644
--- a/gemfiles/common.rb
+++ b/gemfiles/common.rb
@@ -5,3 +5,4 @@
 gem 'maxitest'
 gem 'mocha'
 gem 'rake'
+gem 'ostruct'