diff --git a/lib/opensearch.rb b/lib/opensearch.rb
index 243d0b649..fbf035acc 100644
--- a/lib/opensearch.rb
+++ b/lib/opensearch.rb
@@ -7,6 +7,7 @@
 # This file is generated from the OpenSearch REST API spec.
 # Do not modify it by hand. Instead, modify the generator or the spec.
 
+require 'active_support/all'
 require 'opensearch/transport'
 require 'opensearch/api'
 Dir[File.expand_path('opensearch/api/**/*.rb', __dir__)].sort.each { |f| require f }