diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2ecb9b2..04f38d8c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,14 +4,16 @@
 
 **Enhancements:**
 
-- [#31](github.com/castle/castle-ruby/pull/31/) remove auto-integration with Rails, Padrino, Sinatra (see BREAKING CHANGES, README)
 - [#35](github.com/castle/castle-ruby/pull/35) dropped unused cookie store class, more informative Castle:Client constructor params
+- [#30](github.com/castle/castle-ruby/pull/30) change request timeout to 500ms
+- [#31](github.com/castle/castle-ruby/pull/31) remove auto-integration with Rails, Padrino, Sinatra (see BREAKING CHANGES, README)
 
 **BREAKING CHANGES:**
 
 - add `require 'castle/support/rails'` to have Castle client instance available as `castle` in your Rails controllers
 - add `require 'castle/support/padrino'` to have Castle client instance available as `castle` in your Padrino helpers
 - add `require 'castle/support/sinatra'` to have Castle client instance available as `castle` in your Sinatra helpers
+- request timeout uses milliseconds unit from now on
 
 **Features:**
 
diff --git a/README.md b/README.md
index 71d30387..d57faee1 100644
--- a/README.md
+++ b/README.md
@@ -55,8 +55,8 @@ Castle.configure do |config|
   # Same as setting it through Castle.api_secret
   config.api_secret = 'secret'
 
-  # Castle::RequestError is raised when timing out (default: 30.0)
-  config.request_timeout = 2.0
+  # Castle::RequestError is raised when timing out in seconds (default: 500 milliseconds)
+  config.request_timeout = 2000
 
   # For tracking in non-web environments: https://castle.io/docs/sources (default: 'web')
   config.source_header = 'backend'
diff --git a/lib/castle/api.rb b/lib/castle/api.rb
index 9ef6c7a4..39d6f2bd 100644
--- a/lib/castle/api.rb
+++ b/lib/castle/api.rb
@@ -27,7 +27,7 @@ def prepare_http
         @config_api_endpoint.host,
         @config_api_endpoint.port
       )
-      http.read_timeout = @config.request_timeout
+      http.read_timeout = @config.request_timeout / 1000.0
       prepare_http_for_ssl(http) if @config_api_endpoint.scheme == 'https'
       http
     end
diff --git a/lib/castle/configuration.rb b/lib/castle/configuration.rb
index f1dc2dc5..d34a5269 100644
--- a/lib/castle/configuration.rb
+++ b/lib/castle/configuration.rb
@@ -3,7 +3,8 @@
 module Castle
   # manages configuration variables
   class Configuration
-    REQUEST_TIMEOUT = 30.0
+    SUPPORTED = %i[source_header request_timeout api_secret api_endpoint].freeze
+    REQUEST_TIMEOUT = 500 # in milliseconds
     API_ENDPOINT = 'https://api.castle.io/v1'
     WHITELISTED = [
       'User-Agent',
diff --git a/spec/lib/castle/configuration_spec.rb b/spec/lib/castle/configuration_spec.rb
index 9835eae7..39be032a 100644
--- a/spec/lib/castle/configuration_spec.rb
+++ b/spec/lib/castle/configuration_spec.rb
@@ -64,7 +64,7 @@
 
   describe 'request_timeout' do
     it do
-      expect(config.request_timeout).to be_eql(30.0)
+      expect(config.request_timeout).to be_eql(500)
     end
 
     context 'setter' do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 5f4404d6..f45e3391 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -20,7 +20,6 @@
 RSpec.configure do |config|
   config.before(:each) do
     Castle.config.api_endpoint = 'https://api.castle.io/v1'
-    Castle.config.request_timeout = 30.0
     stub_request(:any, /api.castle.io/)
       .to_return(status: 200, body: '{}', headers: {})
   end