diff --git a/google-apis-core/lib/google/apis/core/base_service.rb b/google-apis-core/lib/google/apis/core/base_service.rb
index 38723fc4d07..a366e5f8432 100644
--- a/google-apis-core/lib/google/apis/core/base_service.rb
+++ b/google-apis-core/lib/google/apis/core/base_service.rb
@@ -557,6 +557,7 @@ def new_client
           Faraday.new options do |faraday|
             faraday.response :logger, Google::Apis.logger if client_options.log_http_requests
             faraday.response :follow_redirects_google_apis_core, limit: 5
+            faraday.adapter client_options.adapter if client_options.adapter
           end
         end
 
diff --git a/google-apis-core/lib/google/apis/options.rb b/google-apis-core/lib/google/apis/options.rb
index 4445f7e90c4..9f8d79be288 100644
--- a/google-apis-core/lib/google/apis/options.rb
+++ b/google-apis-core/lib/google/apis/options.rb
@@ -18,6 +18,7 @@ module Apis
     ClientOptions = Struct.new(
       :application_name,
       :application_version,
+      :adapter,
       :proxy_url,
       :open_timeout_sec,
       :read_timeout_sec,
@@ -50,6 +51,8 @@ class ClientOptions
       #   @return [String] Name of the application, for identification in the User-Agent header
       # @!attribute [rw] application_version
       #   @return [String] Version of the application, for identification in the User-Agent header
+      # @!attribute [rw] adapter
+      #   @return [Symbol, Class] Faraday adapter to use
       # @!attribute [rw] proxy_url
       #   @return [String] URL of a proxy server
       # @!attribute [rw] log_http_requests