diff --git a/lib/who_need_help_web/form_params.ex b/lib/who_need_help_web/form_params.ex
index 3bd982b..93e7083 100644
--- a/lib/who_need_help_web/form_params.ex
+++ b/lib/who_need_help_web/form_params.ex
@@ -10,10 +10,11 @@ defmodule WhoNeedHelpWeb.FormParams do
     |> Enum.reject(fn key ->
       Map.has_key?(data, @live_view_unused_prefix <> to_string(key))
     end)
-    |> MapSet.new(&to_string/1)
+    |> Enum.map(&to_string/1)
+    |> Enum.uniq()
   end
 
-  def touched_structured_keys(_params), do: MapSet.new()
+  def touched_structured_keys(_params), do: []
 
   def drop_unused_structured_fields(%{"structured_data" => data} = params)
       when is_map(data) do
@@ -36,7 +37,7 @@ defmodule WhoNeedHelpWeb.FormParams do
         field ->
           key = to_string(field["key"])
 
-          if submitted? or MapSet.member?(touched_keys, key) do
+          if submitted? or key in touched_keys do
             [{error_kind(message, key), field_label(field, locale)}]
           else
             []
diff --git a/lib/who_need_help_web/live/activity_live/new.ex b/lib/who_need_help_web/live/activity_live/new.ex
index 4b8479b..43d3792 100644
--- a/lib/who_need_help_web/live/activity_live/new.ex
+++ b/lib/who_need_help_web/live/activity_live/new.ex
@@ -13,7 +13,7 @@ defmodule WhoNeedHelpWeb.ActivityLive.New do
      |> assign(:categories, Catalog.list_categories(:activity))
      |> assign(:selected_category, nil)
      |> assign(:structured_fields, [])
-     |> assign(:structured_touched_keys, MapSet.new())
+     |> assign(:structured_touched_keys, [])
      |> assign(:structured_submit_attempted, false)
      |> assign(:form, to_form(Activities.change_activity(%Activity{})))}
   end
@@ -21,9 +21,9 @@ defmodule WhoNeedHelpWeb.ActivityLive.New do
   @impl true
   def handle_event("validate", %{"activity" => params}, socket) do
     touched_keys =
-      MapSet.union(
-        socket.assigns.structured_touched_keys,
-        FormParams.touched_structured_keys(params)
+      Enum.uniq(
+        socket.assigns.structured_touched_keys ++
+          FormParams.touched_structured_keys(params)
       )
 
     params = FormParams.drop_unused_structured_fields(params)
diff --git a/lib/who_need_help_web/live/request_live/new.ex b/lib/who_need_help_web/live/request_live/new.ex
index 4f6de61..1de5e74 100644
--- a/lib/who_need_help_web/live/request_live/new.ex
+++ b/lib/who_need_help_web/live/request_live/new.ex
@@ -27,7 +27,7 @@ defmodule WhoNeedHelpWeb.RequestLive.New do
      |> assign(:categories, Catalog.list_categories())
      |> assign(:selected_category, nil)
      |> assign(:structured_fields, [])
-     |> assign(:structured_touched_keys, MapSet.new())
+     |> assign(:structured_touched_keys, [])
      |> assign(:structured_submit_attempted, false)
      |> assign(:submission_errors, [])
      |> assign(:form, to_form(changeset))}
@@ -36,9 +36,9 @@ defmodule WhoNeedHelpWeb.RequestLive.New do
   @impl true
   def handle_event("validate", %{"help_request" => params}, socket) do
     touched_keys =
-      MapSet.union(
-        socket.assigns.structured_touched_keys,
-        FormParams.touched_structured_keys(params)
+      Enum.uniq(
+        socket.assigns.structured_touched_keys ++
+          FormParams.touched_structured_keys(params)
       )
 
     params = FormParams.drop_unused_structured_fields(params)