diff --git a/app/controllers/concerns/set_platform.rb b/app/controllers/concerns/set_platform.rb
index 54e77d517..66de85f12 100644
--- a/app/controllers/concerns/set_platform.rb
+++ b/app/controllers/concerns/set_platform.rb
@@ -7,6 +7,6 @@ module SetPlatform
 
   private
     def platform
-      @platform ||= ApplicationPlatform.new(request.user_agent)
+      @platform ||= ApplicationPlatform.new(cookies[:x_user_agent].presence || request.user_agent)
     end
 end
diff --git a/test/controllers/concerns/set_platform_test.rb b/test/controllers/concerns/set_platform_test.rb
new file mode 100644
index 000000000..26ce9d66a
--- /dev/null
+++ b/test/controllers/concerns/set_platform_test.rb
@@ -0,0 +1,21 @@
+require "test_helper"
+
+class SetPlatformTest < ActionDispatch::IntegrationTest
+  DESKTOP_UA = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
+  NATIVE_IOS_UA = "Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Hotwire Native iOS/1.0"
+
+  test "uses the request user agent by default" do
+    sign_in_as :david
+
+    get board_path(boards(:writebook)), headers: { "User-Agent" => DESKTOP_UA }
+    assert_match 'data-platform="desktop web"', response.body
+  end
+
+  test "prefers x_user_agent cookie over request user agent" do
+    sign_in_as :david
+
+    cookies[:x_user_agent] = NATIVE_IOS_UA
+    get board_path(boards(:writebook)), headers: { "User-Agent" => DESKTOP_UA }
+    assert_match 'data-platform="native ios"', response.body
+  end
+end