diff --git a/app/decorators/user_decorator.rb b/app/decorators/user_decorator.rb
index dc1851b56..fb52372d5 100644
--- a/app/decorators/user_decorator.rb
+++ b/app/decorators/user_decorator.rb
@@ -80,6 +80,9 @@ class UserDecorator < ApplicationDecorator
       "trusted-status-#{trusted?}",
       "#{setting.config_navbar.tr('_', '-')}-header",
     ]
+
+    # Backfill ten-x-hacker-theme because the ios app looks for it to render native dark shell.
+    body_class << "ten-x-hacker-theme" if setting.config_theme == "dark_theme"
     body_class.join(" ")
   end
 
diff --git a/spec/decorators/user_decorator_spec.rb b/spec/decorators/user_decorator_spec.rb
index 39b1198d8..a7b8c4e9f 100644
--- a/spec/decorators/user_decorator_spec.rb
+++ b/spec/decorators/user_decorator_spec.rb
@@ -98,6 +98,7 @@ RSpec.describe UserDecorator, type: :decorator do
         dark-theme sans-serif-article-body
         mod-status-#{user.admin? || !user.moderator_for_tags.empty?}
         trusted-status-#{user.trusted?} #{user.setting.config_navbar}-header
+        ten-x-hacker-theme
       ].join(" ")
       expect(user.decorate.config_body_class).to eq(expected_result)
     end
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 584363f2c..f9c7e2f27 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -656,7 +656,7 @@ RSpec.describe User do
       user.setting.config_theme = "dark_theme"
 
       # rubocop:disable Layout/LineLength
-      classes = "dark-theme sans-serif-article-body mod-status-#{user.admin? || !user.moderator_for_tags.empty?} trusted-status-#{user.trusted?} #{user.setting.config_navbar}-header"
+      classes = "dark-theme sans-serif-article-body mod-status-#{user.admin? || !user.moderator_for_tags.empty?} trusted-status-#{user.trusted?} #{user.setting.config_navbar}-header ten-x-hacker-theme"
       # rubocop:enable Layout/LineLength
       expect(user.decorate.config_body_class).to eq(classes)
     end