diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index af7939e6..cb122b62 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,6 +22,7 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
+          - '4.0'
           - 3.4
           - 3.3
           - 3.2
diff --git a/Gemfile b/Gemfile
index 4ad94689..75f10ade 100644
--- a/Gemfile
+++ b/Gemfile
@@ -56,3 +56,8 @@ end
 if rails_version.to_s >= '8.1'
   gem 'mongoid', github: 'mongodb/mongoid', ref: 'eac49f0'
 end
+
+# FIXME: Remove after the next mongoid release (will include ostruct dependency)
+if RUBY_VERSION > '4.0.0'
+  gem 'ostruct'
+end