diff --git a/lib/discourse_data_explorer/data_explorer.rb b/lib/discourse_data_explorer/data_explorer.rb
index 8f01b1d..ff43fa5 100644
--- a/lib/discourse_data_explorer/data_explorer.rb
+++ b/lib/discourse_data_explorer/data_explorer.rb
@@ -198,11 +198,9 @@ module ::DiscourseDataExplorer
             .includes(support_info[:include])
             .order(:id)
 
-        ret[cls] = ActiveModel::ArraySerializer.new(
-          all_objs,
-          each_serializer: support_info[:serializer],
-          only: support_info[:only],
-        )
+        opts = { each_serializer: support_info[:serializer] }
+        opts[:only] = support_info[:only] if support_info[:only]
+        ret[cls] = ActiveModel::ArraySerializer.new(all_objs, **opts)
       end
       [ret, col_map]
     end
diff --git a/spec/data_explorer_spec.rb b/spec/data_explorer_spec.rb
index af0385b..9fa562b 100644
--- a/spec/data_explorer_spec.rb
+++ b/spec/data_explorer_spec.rb
@@ -100,6 +100,9 @@ describe DiscourseDataExplorer::DataExplorer do
             records = relations[:topic].object
             records.map { |t| BasicTopicSerializer.new(t, root: false).as_json }
           }.not_to raise_error
+
+          json = relations[:topic].as_json
+          expect(json).to include(BasicTopicSerializer.new(topic, root: false).as_json)
         end
 
         it "chooses the correct serializer for tag_group" do