diff --git a/script/bulk_import/discourse_merger.rb b/script/bulk_import/discourse_merger.rb
index a0801d12410..9de5cd879aa 100644
--- a/script/bulk_import/discourse_merger.rb
+++ b/script/bulk_import/discourse_merger.rb
@@ -218,7 +218,7 @@ class BulkImport::DiscourseMerger < BulkImport::Base
   end
 
   def copy_topics
-    copy_model(Topic, skip_processing: true, mapping: @topics)
+    copy_model(Topic, mapping: @topics)
     [TopicAllowedGroup, TopicAllowedUser, TopicEmbed, TopicSearchData,
       TopicTimer, TopicUser, TopicViewItem
     ].each do |k|
@@ -434,6 +434,11 @@ class BulkImport::DiscourseMerger < BulkImport::Base
     end
   end
 
+  def process_topic(topic)
+    return nil if topic['category_id'].nil?
+    topic
+  end
+
   def process_post(post)
     post[:last_editor_id] = user_id_from_imported_id(post[:user_id])
     @topic_id_by_post_id[post[:id]] = post[:topic_id]