diff --git a/ruby/Gemfile.lock b/ruby/Gemfile.lock
index b172e06f..3fa18005 100644
--- a/ruby/Gemfile.lock
+++ b/ruby/Gemfile.lock
@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     ci-queue (0.77.0)
+      concurrent-ruby
       logger
 
 GEM
diff --git a/ruby/ci-queue.gemspec b/ruby/ci-queue.gemspec
index dd080b4a..a8be80c3 100644
--- a/ruby/ci-queue.gemspec
+++ b/ruby/ci-queue.gemspec
@@ -32,6 +32,7 @@ Gem::Specification.new do |spec|
   spec.metadata['allowed_push_host'] = 'https://rubygems.org'
 
   spec.add_runtime_dependency 'logger'
+  spec.add_runtime_dependency 'concurrent-ruby'
 
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'rake'