diff --git a/app/presenters/hotwire_combobox/component/markup/dialog.rb b/app/presenters/hotwire_combobox/component/markup/dialog.rb
index 3a0a901..cba6989 100644
--- a/app/presenters/hotwire_combobox/component/markup/dialog.rb
+++ b/app/presenters/hotwire_combobox/component/markup/dialog.rb
@@ -5,7 +5,7 @@ def dialog_wrapper_attrs
 
   def dialog_attrs
     customize :dialog, base: {
-      class: "hw-combobox__dialog #{platform_classes}", role: :dialog, data: {
+      class: "hw-combobox__dialog", role: :dialog, data: {
       action: "keydown->hw-combobox#navigate", hw_combobox_target: "dialog" } }
   end
 
@@ -34,15 +34,6 @@ def dialog_focus_trap_attrs
   end
 
   private
-    def platform_classes
-      platform = HotwireCombobox::Platform.new request&.user_agent
-
-      view.token_list \
-        "hw-combobox--ios": platform.ios?,
-        "hw-combobox--android": platform.android?,
-        "hw-combobox--mobile-webkit": platform.mobile_webkit?
-    end
-
     def dialog_input_id
       "#{canonical_id}-hw-dialog-combobox"
     end
diff --git a/app/presenters/hotwire_combobox/component/markup/fieldset.rb b/app/presenters/hotwire_combobox/component/markup/fieldset.rb
index c630463..6990ad6 100644
--- a/app/presenters/hotwire_combobox/component/markup/fieldset.rb
+++ b/app/presenters/hotwire_combobox/component/markup/fieldset.rb
@@ -1,10 +1,19 @@
 module HotwireCombobox::Component::Markup::Fieldset
   def fieldset_attrs
     customize :fieldset, base: {
-      class: [ "hw-combobox", { "hw-combobox--multiple": multiselect? } ], data: fieldset_data }
+      class: [ "hw-combobox", platform_classes, { "hw-combobox--multiple": multiselect? } ], data: fieldset_data }
   end
 
   private
+    def platform_classes
+      platform = HotwireCombobox::Platform.new request&.user_agent
+
+      view.token_list \
+        "hw-combobox--ios": platform.ios?,
+        "hw-combobox--android": platform.android?,
+        "hw-combobox--mobile-webkit": platform.mobile_webkit?
+    end
+
     def fieldset_data
       data.merge \
         async_id: canonical_id,