diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 7ed36161cb..be5c9ff972 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -67,6 +67,9 @@ def locale_from_request_params
   end
 
   def set_locale
+    # Prevent leaking of I18n.locale between requests
+    I18n.locale = I18n.default_locale
+
     return unless Flipper.enabled?(:localization, current_user)
     # TODO: Remove debug logging when feature flag is removed
 
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index bbfb869904..71352a9458 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -78,9 +78,8 @@
     # (Un-stub before each example as needed, overriding with specific args)
     allow(Flipper).to receive(:enabled?).with(any_args).and_call_original
 
-    # Reset locale settings to defaults
+    # Reset default locale between examples
     I18n.default_locale = :en
-    I18n.locale = I18n.default_locale
   end
 end