diff --git a/lib/govuk_app_config/govuk_xray.rb b/lib/govuk_app_config/govuk_xray.rb
index <HASH>..<HASH> 100644
--- a/lib/govuk_app_config/govuk_xray.rb
+++ b/lib/govuk_app_config/govuk_xray.rb
@@ -16,6 +16,7 @@ module GovukXRay
       name: ENV['GOVUK_APP_NAME'].to_s,
       patch: patch,
       sampling_rules: {
+        version: 1,
         default: {
           'fixed_target': ENV.fetch('XRAY_SAMPLE_TARGET', 0).to_i,
           'rate': ENV.fetch('XRAY_SAMPLE_RATE', 0.01).to_f,
Specify the version of the sampling rules