diff --git a/plugin.rb b/plugin.rb
index 84eaf87..31f44ac 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -34,20 +34,5 @@ def can_create_post_on_topic?(topic)
     Guardian.class_exec do
       prepend topic_overrides
     end
-
-    category_overrides = Module.new do
-      def category_params
-        return super if !SiteSetting.restricted_replies_enabled
-        super.tap do |value|
-          if params["custom_fields"] && groups = params["custom_fields"]["restrict_replies_bypass_groups"]
-            value["custom_fields"]["restrict_replies_bypass_groups"] = groups
-          end
-        end
-      end
-    end
-
-    CategoriesController.class_exec do
-      prepend category_overrides
-    end
   end
 end
diff --git a/spec/requests/categories_controller_spec.rb b/spec/requests/categories_controller_spec.rb
new file mode 100644
index 0000000..dca3eeb
--- /dev/null
+++ b/spec/requests/categories_controller_spec.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+describe CategoriesController do
+  let(:admin) { Fabricate(:admin) }
+  let!(:category) { Fabricate(:category, user: admin) }
+
+  context '#update' do
+    before do
+      SiteSetting.restricted_replies_enabled = true
+      sign_in(admin)
+    end
+
+    it "updates `restrict_replies_bypass_groups` custom field correctly" do
+      readonly = CategoryGroup.permission_types[:readonly]
+      create_post = CategoryGroup.permission_types[:create_post]
+      tag_group = Fabricate(:tag_group)
+
+      put "/categories/#{category.id}.json", params: {
+        name: "hello",
+        color: "ff0",
+        text_color: "fff",
+        slug: "hello-category",
+        auto_close_hours: 72,
+        custom_fields: {
+          "restrict_replies": true,
+          "restrict_replies_bypass_groups" => [1, 2]
+        }
+      }
+
+      expect(response.status).to eq(200)
+      category.reload
+      expect(category.custom_fields).to eq("restrict_replies" => true, "restrict_replies_bypass_groups" => [1, 2])
+    end
+  end
+end