diff --git a/app/views/categories/_form.html.erb b/app/views/categories/_form.html.erb
index 8927c0bf..06426988 100644
--- a/app/views/categories/_form.html.erb
+++ b/app/views/categories/_form.html.erb
@@ -34,7 +34,7 @@
       <div class="space-y-2">
         <%= f.select :classification, [["Income", "income"], ["Expense", "expense"]], { label: "Classification" }, required: true %>
         <%= f.text_field :name, placeholder: t(".placeholder"), required: true, autofocus: true, label: "Name", data: { color_avatar_target: "name" } %>
-        <%= f.select :parent_id, categories.pluck(:name, :id), { include_blank: "(unassigned)", label: "Parent category (optional)" } %>
+        <%= f.select :parent_id, categories.pluck(:name, :id), { include_blank: "(unassigned)", label: "Parent category (optional)" }, disabled: category.parent? %>
       </div>
     </section>